No Nonscense – Getting Machine With Ip From Rounter Back Up + Adding New Machine That Is Not Getting IP.

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These exact steps apply with zero change on any machine (Mac, PC, Linux box, or mini-server) as long as the OS uses a normal Ethernet NIC and DHCP client.:

  • Ubuntu, Debian, or AlmaLinux — native or dual-booted Macs or PCs

  • Intel Mac Minis running Linux (yours)

  • MinisForum or other small PCs running Linux

  • Old MacBooks running Ubuntu or Debian

    Because:

    • All of them use a standard network interface (enpXsY, eth0, etc.)
    • All use ip, dhclient, and /etc/systemd/network/ syntax
    • All rely on the same DHCP handshake protocol (discover → offer → request → ack)

🧰 STEP-BY-STEP: bring a previously active with a ip address set in the router back onto the LAN

(works on any Ubuntu/Debian/Alma variant; adapt only the interface name if different)

1️⃣ Identify the interface

ip link show
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Look for a line like

2: enp1s0f0: <BROADCAST,MULTICAST,DOWN> ...
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That’s your Ethernet NIC name.

Save it as a variable to make the next steps easy:

IF=enp1s0f0     # replace with what you saw
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2️⃣ Bring it up cleanly

sudo ip link set "$IF" up
sudo ip addr flush dev "$IF"
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3️⃣ Try DHCP first

Use this to get machines that had an IP / were working correclty back up 

RUN THIS: for macines that previously had an address
sudo ip link set "$IF" up
sudo dhclient -r "$IF" && sudo dhclient "$IF"
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Use this if you need to install a dhcp client

sudo apt update && sudo apt install -y isc-dhcp-client
sudo dhclient -r "$IF" && sudo dhclient "$IF"
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Check:

ip -br a show dev "$IF"
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✅ If you see 192.168.1.x, stop — you’re good.

❌ If still blank/127.0.0.1, continue.

4️⃣ Assign a static IP (your reserved one)

Example for proxy = 192.168.1.26; adjust as needed:

sudo ip addr add 192.168.1.26/24 dev "$IF"
sudo ip route add default via 192.168.1.1
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Then test:

ping -c3 192.168.1.1
ping -c3 8.8.8.8
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5️⃣ Make it permanent

Create /etc/systemd/network/10-$IF.network:

sudo tee /etc/systemd/network/10-$IF.network >/dev/null <<EOF
[Match]
Name=$IF

[Network]
Address=192.168.1.26/24
Gateway=192.168.1.1
DNS=1.1.1.1 8.8.8.8
EOF
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Enable the manager and apply:

sudo systemctl enable --now systemd-networkd
sudo systemctl restart systemd-networkd
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Re-check:

ip -br a show dev "$IF"
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You should now see the static address and, within a few seconds, both machines will reappear in the router’s list.

🧩 Why this fixes it

  • 127.0.0.1 means no interface was configured; the OS is only talking to itself.
  • Bringing the link up + DHCP tries to get an IP from the router.
  • The fallback static address forces it to join the LAN even if DHCP fails.
  • systemd-networkd keeps it persistent across boots (no Netplan needed).

After you do this once on each affected Mac, they’ll stay visible in the router and reachable over the LAN even after restarts or cable swaps.

Adding a new machine – that will not pick up and address

🧰 STEP-BY-STEP: Add a new machine (no router entry, no IP yet)

(Works on any Ubuntu / Debian / AlmaLinux system — identical on Intel Macs, MinisForum boxes, or PCs)

1️⃣ Identify the interface

ip link show
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Look for something like:

2: enp1s0f0: <BROADCAST,MULTICAST,DOWN> ...
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Save it for reuse:

IF=enp1s0f0     # replace with the actual interface name
JavaScript

2️⃣ Bring it up cleanly

sudo ip link set "$IF" up
sudo ip addr flush dev "$IF"
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3️⃣ Make sure you have a DHCP client

Check whether dhclient exists:

command -v dhclient || echo "no dhclient"
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If missing:

sudo apt update && sudo apt install -y isc-dhcp-client
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4️⃣ Try DHCP to request an address from the router

sudo dhclient -r "$IF" 2>/dev/null
sudo dhclient "$IF"
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Check:

ip -br a show dev "$IF"
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✅ If you see something like 192.168.1.42/24 → you’re done.

❌ If you still see 127.0.0.1 or blank, continue.

5️⃣ Manually assign a temporary static IP

Choose an address inside your LAN range but outside the DHCP pool (e.g. 192.168.1.240–249).

sudo ip addr add 192.168.1.240/24 dev "$IF"
sudo ip route add default via 192.168.1.1
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Test basic reachability:

ping -c3 192.168.1.1
ping -c3 8.8.8.8
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If those succeed → your NIC, switch, and cable all work fine.

6️⃣ Reserve the IP in your router

  1. Go to your router’s LAN / DHCP Reservation page.
  2. Find the new machine’s MAC address:
cat /sys/class/net/$IF/address
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  1. Add a reservation for it (e.g. 192.168.1.40).
  2. Save and power-cycle the router for 30 seconds so leases refresh.

After that:

sudo dhclient -r "$IF" && sudo dhclient "$IF"
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You should now get the reserved IP automatically.

Once you confirm the new machine gets its proper IP:

sudo tee /etc/systemd/network/10-$IF.network >/dev/null <<EOF
[Match]
Name=$IF

[Network]
DHCP=yes
FallbackDNS=1.1.1.1 8.8.8.8
EOF
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Then enable and reload the network service:

sudo systemctl enable --now systemd-networkd
sudo systemctl restart systemd-networkd
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Re-check:

ip -br a show dev "$IF"
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🧩 Why this works

  • A brand-new device has no prior DHCP lease, so the router doesn’t “know” it yet.
  • Bringing the interface up and explicitly requesting a lease forces a full DHCP discover → offer → request → ack cycle.
  • If DHCP fails (router table full, or client not recognized), a static address confirms hardware and switch are functional.
  • Reserving the IP in the router permanently maps its MAC → IP so future boots get it instantly.

Optional Universal Static IP / Self Heal

(OPTIONAL) 🧰 UNIVERSAL STATIC-IP + SELF-HEAL SETUP (for any Ethernet device)


Perfect plan. You’ll run the full unified steps so every machine gets reset and configured cleanly—no mix of half-fixes.
Here’s the final complete set including the self-heal (same for any Linux box, just swap the IP and interface name).

1️⃣ Physically clear router tables

Unplug router 30 s → plug back in → wait 2–3 min.

Step 1 – Verify unique MACs

On each machine, run: 

ip link show | grep ether
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and confirm every address in that list is unique. If any two match, change one in the system (e.g., in NetworkManager or /etc/netplan). When you ran: 

ip link show | grep ether
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you should see lines like: 

link/ether 0c:4d:e9:b5:26:aa brd ff:ff:ff:ff:ff:ff
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That 0c:4d:e9:b5:26:aa is your MAC address —

✅ OTHER CHECKS FOR REVERSE PROXY / MACHHINES

1. Run this: 

ip -br a
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1. You’ll see all your interfaces in one line, e.g. 

lo               UNKNOWN        127.0.0.1/8 ::1/128
enp1s0f0         UP             fe80::1234:abcd:ef56:7890/64
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1. That shows whether enp1s0f0 has only IPv6 right now (fe80::…) and no IPv4 (192.168.x.x) — which matches your “it has IPv6 but no real IP” issue. 2. Run this next: 

sudo ethtool enp1s0f0 | grep Speed
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1. to confirm it’s still linking at 1000 Mb/s (so hardware’s fine). 2. Then check its MAC directly: 

cat /sys/class/net/enp1s0f0/address
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1. That prints the exact hardware MAC. We’ll match it against your router’s reservation list (looks like 0C:4D:E9:B5:26:AA from your screenshot). Once you confirm the MAC from the cat command above: ✅ CHECK MAC ADDRESS IS CORRECT IN ROUTER 1. Go into your router’s Address Reservation page. Make sure that exact MAC → 192.168.1.26 (your proxy) is correct. If not, edit that reservation to match what cat /sys/…/address shows. ✅ Then Fix the machine 1. Back on the proxy, flush and renew the IP: 

sudo dhclient -r enp1s0f0
sudo dhclient enp1s0f0
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or FLUSH This does everything the first version does plus wipes all IPs (IPv4 + IPv6) and routes off that NIC — a deeper reset. 

sudo dhclient -r enp1s0f0
sudo ip addr flush dev enp1s0f0
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If it still doesn’t get one, assign it static manually: 

sudo ip addr add 192.168.1.44/24 dev enp1s0f0
sudo ip route add default via 192.168.1.1
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That will instantly restore IPv4 connectivity if the hardware and MAC mapping are correct. If you paste just the output from: 

cat /sys/class/net/enp1s0f0/address
ip -br a
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To confirm whether your MAC matches the router reservation and tell you the exact next 2 commands to bring it back online.

Step 3 – Lock down static IPs for key servers

Keep the reserved IPs for everything that acts as infrastructure (NAS, proxy, etc.) and make sure those devices themselves are set to manual/static IPs inside the OS — not “DHCP with reservation.” Example: in your proxy’s /etc/netplan/01-netcfg.yaml: 

enp1s0f0:
  dhcp4: no
  addresses: [192.168.1.44/24]
  gateway4: 192.168.1.1
  nameservers:
    addresses: [1.1.1.1, 8.8.8.8]
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Step 4 – Optional safety

If you’re running containers or bridges on that proxy, add this to /etc/docker/daemon.json (or equivalent) 

{
  "macaddress": "02:42:ac:11:00:02"
}
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so Docker stops generating NICs that might spoof your real MAC. Once every machine has a unique MAC and your router’s tables are cleared, new devices will never knock the proxy offline again — even if you plug in ten at once.

also optional

(optional) Check for netplan

Excellent — that’s the right question before you start editing anything. You want to verify that this machine actually uses Netplan (and not NetworkManager or ifcfg scripts) and make sure it’s properly registered in th system. Heres the full, safe check process 👇

🧩 Step 1 – Check if Netplan is installed


which netplan
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✅ If it returns something like /usr/sbin/netplan, you already have it.

BACK IT UP BEFORE MAKING CHANGES

🧰BACKUP NETPLAN CONFIG**


sudo mkdir -p /root/netplan-backups
sudo cp /etc/netplan/*.yaml /root/netplan-backups/
sudo netplan get > /root/netplan-backups/current-netplan.yaml
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🧰RESTORE NETPLAN CONFIG**


sudo cp /root/netplan-backups/*.yaml /etc/netplan/
sudo netplan apply
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END BACK IT UP BEFORE MAKING CHANGES

❌ If it says “not found”, install it: 

sudo apt update
sudo apt install netplan.io -y
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🧩 Step 2 – Confirm Netplan controls the interface

Run: 

ls /etc/netplan/
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If you see any .yaml file (e.g. 01-netcfg.yaml, 50-cloud-init.yaml, 01-static.yaml), Netplan is active. You can confirm which renderer it’s using: 

grep renderer /etc/netplan/*.yaml
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Typical result: – renderer: networkd → good for servers – renderer: NetworkManager → used on desktops Either way, Netplan is the frontend controlling networking.

*🧩 Step 3 – Check which backend actually runs the network


sudo networkctl list
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If you see your interface (like enp1s0f0) in that list, systemd-networkd is managing it — that’s the backend Netplan uses. If instead you see: 

nmcli device status
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showing your interface as “connected”, then NetworkManager is handling it. (That’s fine too — Netplan just passes control to it.)

🧩 Step 4 – Cache and confirm current Netplan state

Dump the active Netplan plan into a readable file: 

sudo netplan get > ~/current-netplan.yaml
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Now you’ve “cached” the current configuration in your home folder. If anything goes wrong later, you can restore it with 

sudo netplan set --from-file ~/current-netplan.yaml
sudo netplan apply
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🧠 TL;DR Summary

– ✅ which netplan → proves it’s installed – ✅ ls /etc/netplan/ → proves it’s managing the network – ✅ sudo netplan get → saves your current plan for safekeeping Once you confirm those, you can safely edit /etc/netplan/01-static.yaml to add your static IP knowing this machine is indeed governed by Netplan.

Explanation

Excellent — that screenshot helps a lot. You’ve clearly done the right thing: everything important has a reserved IP in the router, so on paper there shouldn’t be conflicts.

But your pattern still makes sense, because there’s a subtler failure mode hiding behind this setup. Let’s break it down:

⚠️ Why this can still happen

Even with DHCP reservations, two things can still knock a Linux proxy offline:

1️⃣ Duplicate MAC or bridge ghosting

If any device (old VM, docker container, USB NIC, or Thunderbolt bridge) on the proxy uses the same MAC address as another reserved host, the router gets confused — it will see two MACs claiming the same IP and “silently” pick one.

👉 Notice in your screenshot:

  • SHAWNEEE-MINI Ethernet → 5C:1B:F4:8D:49:28
  • PROXY GOGOMAC ETHO → 38:F9:D3:10:54:8A
  • SPIFFY-MINI and SPIFFY-SUPER-MINI-PROXY both start with 0C:4D:E9…

Those last two share the same vendor block (0C:4D:E9 = same NIC family). If one interface or virtual NIC cloned the other’s full MAC, the router could intermittently “replace” one device with the other — exactly the behavior you see.

2️⃣ Router ARP table or DHCP table not flushing correctly

When you add a new device, the router updates its ARP cache. Some Nighthawks (especially the AX12) have a firmware bug where stale ARP entries cause traffic for one IP to route to another MAC until the entry ages out (≈20 hours).

That’s why it “fixes itself” overnight.

🧰 Fix it permanently

Here’s how to stop this cycle:

Step 2 – Clear the router’s ARP & DHCP caches

NETGEAR have to unplug for 30 seconds!!!!!!

In the Nighthawk web UI:

  • Go to Advanced → Administration → Diagnostics

  • Click Clear ARP Table and Clear DHCP Leases (or reboot the router).

    That forces it to relearn each device’s MAC ↔ IP mapping cleanly.

Step 1 – Verify unique MACs

On each machine, run:

ip link show | grep ether
JavaScript

and confirm every address in that list is unique.

If any two match, change one in the system (e.g., in NetworkManager or /etc/netplan).

When you ran:

ip link show | grep ether
JavaScript

you should see lines like:

link/ether 0c:4d:e9:b5:26:aa brd ff:ff:ff:ff:ff:ff
JavaScript

That 0c:4d:e9:b5:26:aa is your MAC address —

✅ OTHER CHECKS FOR REVERSE PROXY / MACHHINES

  1. Run this:
ip -br a
JavaScript
  1. You’ll see all your interfaces in one line, e.g.
lo               UNKNOWN        127.0.0.1/8 ::1/128
enp1s0f0         UP             fe80::1234:abcd:ef56:7890/64
JavaScript
  1. That shows whether enp1s0f0 has only IPv6 right now (fe80::…) and no IPv4 (192.168.x.x) — which matches your “it has IPv6 but no real IP” issue.
  2. Run this next:
sudo ethtool enp1s0f0 | grep Speed
JavaScript
  1. to confirm it’s still linking at 1000 Mb/s (so hardware’s fine).
  2. Then check its MAC directly:
cat /sys/class/net/enp1s0f0/address
JavaScript

  1. That prints the exact hardware MAC.

    We’ll match it against your router’s reservation list (looks like 0C:4D:E9:B5:26:AA from your screenshot).

Once you confirm the MAC from the cat command above:

✅ CHECK MAC ADDRESS IS CORRECT IN ROUTER

  1. Go into your router’s Address Reservation page.

    Make sure that exact MAC → 192.168.1.26 (your proxy) is correct.

    If not, edit that reservation to match what cat /sys/…/address shows.

✅ Then Fix the machine

  1. Back on the proxy, flush and renew the IP:
sudo dhclient -r enp1s0f0
sudo dhclient enp1s0f0
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or FLUSH

This does everything the first version does plus wipes all IPs (IPv4 + IPv6) and routes off that NIC — a deeper reset.

sudo dhclient -r enp1s0f0
sudo ip addr flush dev enp1s0f0
JavaScript

If it still doesn’t get one, assign it static manually:

sudo ip addr add 192.168.1.44/24 dev enp1s0f0
sudo ip route add default via 192.168.1.1
JavaScript

That will instantly restore IPv4 connectivity if the hardware and MAC mapping are correct.

If you paste just the output from:

cat /sys/class/net/enp1s0f0/address
ip -br a
JavaScript

To confirm whether your MAC matches the router reservation and tell you the exact next 2 commands to bring it back online.

Step 3 – Lock down static IPs for key servers

Keep the reserved IPs for everything that acts as infrastructure (NAS, proxy, etc.)

and make sure those devices themselves are set to manual/static IPs inside the OS — not “DHCP with reservation.”

Example: in your proxy’s /etc/netplan/01-netcfg.yaml:

enp1s0f0:
  dhcp4: no
  addresses: [192.168.1.44/24]
  gateway4: 192.168.1.1
  nameservers:
    addresses: [1.1.1.1, 8.8.8.8]
JavaScript

Step 4 – Optional safety

If you’re running containers or bridges on that proxy, add this to /etc/docker/daemon.json (or equivalent):

{
  "macaddress": "02:42:ac:11:00:02"
}
JavaScript

so Docker stops generating NICs that might spoof your real MAC.

Once every machine has a unique MAC and your router’s tables are cleared, new devices will never knock the proxy offline again — even if you plug in ten at once.

If you’d like, I can help you extract the MACs from each system’s ip link show output and spot any duplicates before you start clearing things. Would you like to do that?# No nonscense – getting machine with ip from rounter back up + adding new machine that is not getting IP.

These exact steps apply with zero change on any machine (Mac, PC, Linux box, or mini-server) as long as the OS uses a normal Ethernet NIC and DHCP client.:

  • Ubuntu, Debian, or AlmaLinux — native or dual-booted Macs or PCs

  • Intel Mac Minis running Linux (yours)

  • MinisForum or other small PCs running Linux

  • Old MacBooks running Ubuntu or Debian

    Because:

    • All of them use a standard network interface (enpXsY, eth0, etc.)
    • All use ip, dhclient, and /etc/systemd/network/ syntax
    • All rely on the same DHCP handshake protocol (discover → offer → request → ack)

🧰 STEP-BY-STEP: bring a previously active with a ip address set in the router back onto the LAN

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sudo systemctl enable --now systemd-networkd
sudo systemctl restart systemd-networkd
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sudo systemctl enable --now systemd-networkd
sudo systemctl restart systemd-networkd
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more stuff belwo

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