I run Ubuntu Desktop as a server to serve media (Emby), DNS (Pihole), and files (Samba). I use SSH to manage the server.
Whenever I try to transfer large files to the server regardless of destination drive, the transfer gets interrupted after 100MB-6GB, as do my SSH connections. I also lose the ability to ping the server. This happens whether I transfer over Samba or over SCP. This does NOT happen when I stream media from the server, i.e. when the server is sending, rather than receiving. But the machine itself doesn't crash -- I confirmed by having a cron job to write the current time to a text file every minute, and these writes continue after disconnection.
I tried setting up a monit task to check if the WiFi interface is down and to restart it. I tried two separate checks -- pinging the router and checking if the interface was down. The router ping check is triggered first. The interface down is triggered later. But restarting the interface does not reestablish the connection -- I tried both using ifconfig and nmcli in the monit command, and neither restores ping- or ssh-ability. Only restarting the server using the power buton works.
NetworkManager and dmesg logs don't show anything interesting. syslog has the following unusual bit right around the time the connection is interrupted:
Oct 20 22:15:21 systemd[1]: Starting Cleanup of Temporary Directories...
Oct 20 22:15:21 systemd[1]: systemd-tmpfiles-clean.service: Deactivated successfully.
Oct 20 22:15:21 systemd[1]: Finished Cleanup of Temporary Directories.
Oct 20 22:15:49 NetworkManager[622]: <info> [1697854549.6410] manager: NetworkManager state is now CONNECTED_SITE
Oct 20 22:15:49 dbus-daemon[621]: [system] Activating via systemd: service name='org.freedesktop.nm_dispatcher' unit='dbus-org.freedesktop.nm-dispatcher.service' requested by ':1.12' (uid=0 pid=622 comm="/usr/sbin/NetworkManager --no-daemon " label="unconfined")
Oct 20 22:15:49 systemd[1]: Starting Network Manager Script Dispatcher Service...
Oct 20 22:15:49 dbus-daemon[621]: [system] Successfully activated service 'org.freedesktop.nm_dispatcher'
Oct 20 22:15:49 systemd[1]: Started Network Manager Script Dispatcher Service.
Oct 20 22:15:52 systemd-resolved[544]: Using degraded feature set UDP instead of UDP+EDNS0 for DNS server 192.168.1.10.
Oct 20 22:15:59 systemd[1]: NetworkManager-dispatcher.service: Deactivated successfully.
Oct 20 22:16:53 systemd-resolved[544]: Using degraded feature set TCP instead of UDP for DNS server 192.168.1.10.
Oct 20 22:17:01 CRON[2326]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Oct 20 22:18:13 systemd-timesyncd[546]: Timed out waiting for reply from 185.125.190.57:123 (ntp.ubuntu.com).
Oct 20 22:18:24 systemd-timesyncd[546]: Timed out waiting for reply from 185.125.190.58:123 (ntp.ubuntu.com).
Oct 20 22:18:34 systemd-timesyncd[546]: Timed out waiting for reply from 91.189.91.157:123 (ntp.ubuntu.com).
Oct 20 22:18:44 systemd-timesyncd[546]: Timed out waiting for reply from 185.125.190.56:123 (ntp.ubuntu.com).
Oct 20 22:20:07 systemd-resolved[544]: Using degraded feature set UDP instead of TCP for DNS server 192.168.1.10.
My WiFi card has a Broadcom chipset and is set up as per Special Case #3 here: Installing Broadcom Wireless Drivers
That is, with the bcmwl-kernel-source driver and the following /etc/rc.local:
#!/bin/bash
modprobe -r b44 b43 b43leacy ssb brcmsmac bcma
modprobe -rf wl
modprobe -vv wl
Power management and IPv6 is turned off. I tried stopping Pi-hole, and that didn't help either.
I tried to keep descriptions of what I've tried concise. Please let me know if I can provide additional details, and I will edit this post accordingly. Thank in advance for your help, because I'm stumped...
