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I have a printer that keeps disappearing from the network.

Setup: Printer(static ip) ))) strong wireless link ((( OpenWrt router (hostname mapping) <--> wires to computers (connect to printer via hostname)

Device restarts didn't help. DNS lookups are always working. The IP address is assigned to the device's MAC address in DNSmasq static leases, with no IP address conflicts. It seems to be an ARP issue. Does the router forget the MAC address for it sometimes? LibreNMS has shown it responded well for the past two months, then something changed 2 days ago (but it did get a response 27 minutes ago). I guess the printer could be buggy? Maybe I need to restart harder? Is there a way to know why the ARP is failing? some sort of logging or probing?

root@TP-link-Archer-A6:~# arp
IP address       HW type     Flags       HW address            Mask     Device
...
192.168.1.108    0x1         0x0         00:00:00:00:00:00     *        br-lan
...

root@TP-link-Archer-A6:~# ip neigh show
...
192.168.1.108 dev br-lan  used 0/0/0 probes 6 FAILED
...
2601:681:617f:6f5:7446:da57:49bc:f817 dev br-lan  used 0/0/0 probes 6 FAILED
...

root@TP-link-Archer-A6:~# ip neigh show | grep 77

root@TP-link-Archer-A6:~# ip neighbor add 192.168.1.108  lladdr 74:29:AF:39:77:3D nud permanent dev br-lan

root@TP-link-Archer-A6:~# arp -s 192.168.1.108 74:29:AF:39:77:3D -i br-lan

root@TP-link-Archer-A6:~# arp
IP address       HW type     Flags       HW address            Mask     Device
...
192.168.1.108    0x1         0x0         00:00:00:00:00:00     *        br-lan
...

root@TP-link-Archer-A6:~# ip neigh show | grep 77
192.168.1.108 dev br-lan lladdr 74:29:af:39:77:3d used 0/0/0 probes 6 STALE

root@TP-link-Archer-A6:~# arp
IP address       HW type     Flags       HW address            Mask     Device
...
192.168.1.108    0x1         0x2         74:29:af:39:77:3d     *        br-lan
...

root@TP-link-Archer-A6:~# ping printer.lan
PING printer.lan (192.168.1.108): 56 data bytes
64 bytes from 192.168.1.108: seq=0 ttl=255 time=117.447 ms
64 bytes from 192.168.1.108: seq=1 ttl=255 time=4.975 ms
64 bytes from 192.168.1.108: seq=2 ttl=255 time=3.110 ms
64 bytes from 192.168.1.108: seq=3 ttl=255 time=2.585 ms
^C
--- printer.lan ping statistics ---
4 packets transmitted, 4 packets received, 0% packet loss
round-trip min/avg/max = 2.585/32.029/117.447 ms

root@TP-link-Archer-A6:~# ip neigh show | grep 77
192.168.1.108 dev br-lan lladdr 74:29:af:39:77:3d used 0/0/0 probes 1 STALE

root@TP-link-Archer-A6:~# ping printer.lan
PING printer.lan (192.168.1.108): 56 data bytes
^C
--- printer.lan ping statistics ---
8 packets transmitted, 0 packets received, 100% packet loss

root@TP-link-Archer-A6:~# ip neigh show | grep 77

root@TP-link-Archer-A6:~# ip neigh show | grep 77

root@TP-link-Archer-A6:~# ping printer.lan
PING printer.lan (192.168.1.108): 56 data bytes
^C
--- printer.lan ping statistics ---
9 packets transmitted, 0 packets received, 100% packet loss

root@TP-link-Archer-A6:~# ping printer.lan
PING printer.lan (192.168.1.108): 56 data bytes
64 bytes from 192.168.1.108: seq=5 ttl=255 time=225.002 ms
64 bytes from 192.168.1.108: seq=7 ttl=255 time=133.938 ms
^C
--- printer.lan ping statistics ---
10 packets transmitted, 2 packets received, 80% packet loss
round-trip min/avg/max = 133.938/179.470/225.002 ms

root@TP-link-Archer-A6:~# ping printer.lan
PING printer.lan (192.168.1.108): 56 data bytes
64 bytes from 192.168.1.108: seq=6 ttl=255 time=460.652 ms
64 bytes from 192.168.1.108: seq=8 ttl=255 time=659.703 ms
64 bytes from 192.168.1.108: seq=10 ttl=255 time=208.943 ms
64 bytes from 192.168.1.108: seq=12 ttl=255 time=958.312 ms
64 bytes from 192.168.1.108: seq=14 ttl=255 time=977.629 ms
64 bytes from 192.168.1.108: seq=16 ttl=255 time=546.929 ms
64 bytes from 192.168.1.108: seq=17 ttl=255 time=176.548 ms
64 bytes from 192.168.1.108: seq=27 ttl=255 time=183.175 ms
64 bytes from 192.168.1.108: seq=31 ttl=255 time=131.461 ms
^C
--- printer.lan ping statistics ---
32 packets transmitted, 9 packets received, 71% packet loss
round-trip min/avg/max = 131.461/478.150/977.629 ms
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  • Are there more routers/access points serving the same Wi-Fi SSID, or just this one? Commented 16 hours ago
  • Only this one access point with this SSID. Commented 13 hours ago
  • After letting it sit for several hours, it started working again. It would still be good to know some more options to try. Commented 12 hours ago
  • Hold up, you've got a shitty Wi-Fi link (or overall network situation) in general. Even when it's working, you're seeing 80% packet loss and nearly full-second ping times? You've got something a lot worse than a disappearing printer happening on your network. Commented 11 hours ago

1 Answer 1

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The most common cause for problems like this is a buggy Wi-Fi implementation causing a Wi-Fi group key rotation failure, which breaks multicast and broadcast, which breaks ARP. The buggy Wi-Fi implementation could be your AP (wireless router), or your printer, or the device that's trying to find the printer (well, in your case it sounds like the device trying to find the printer isn't on Wi-Fi, so it wouldn't be that device's Wi-Fi implementation in that case).

Leaving original WPA (TKIP) enabled as an option makes group key handling extra tricky, which can expose more bugs. So make sure you don't have original WPA (TKIP) enabled in any way. WPA2-only (AES-CCMP only), or mixed mode WPA2/WPA3 is fine, but never let original WPA (TKIP) be available. But even completely disabling original WPA doesn't prevent you from hitting other potential bugs that could cause group key handling failures.

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  • Upon review, I see that OP's Wi-Fi latency and packet loss are terrible even when things are "working", so in OP's particular case, something else may be going on. I think I'll leave this Answer up though, because it'll help most people that come here with similar symptoms. Commented 11 hours ago
  • Thanks, those look like good things to look at. It is set to WPA2-PSK. Cipher is set to auto. I could try setting it to force something that isn't TKIP, but it seems that auto picked CCMP. Commented 11 hours ago

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