SSH and HTTP connections via WiFi fail intermittently

janeden

10/15/23, 3:02 PM

I recently installed Ubuntu 22.04 with OpenSSH server and nginx on a Lenovo ThinkPad. The host is connected to the local network via WiFi. Local connections (via SSH or HTTP) to the host sometimes only work from specific clients, while other clients return an error (time out/no route to host/host is down). The failed connection attempts do not appear in /var/log/auth.log.

The issue can be fixed reliably (but only temporarily) by initiating any connection (e.g. ping) from the host to the client incapable of establishing a connection: As soon as a single packet arrives back from the client, the connection to the host succeeds. ufw is configured to allow both HTTP/port 80 and SSH/port 22 connections to the host from all clients in the local network.

Power management and expiring DHCP leases as causes do not seem plausible, as the problem occurs per client.

Another Ubuntu server (Intel NUC) connected via Ethernet and configured similarly does not exhibit this behaviour.

Thanks in advance for any hints in the right direction.

Cheers, Jan

0 + 2

server

wireless

networking

lan

FedKad

10/15/23, 3:16 PM

You may try to change the MTU size (match to one working OK or make it even smaller).

janeden

10/15/23, 3:43 PM

Thanks, but the connections from all clients work well (once I connect to the client from the host), and all clients are sometimes affected by the problem.

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