Many people have mentioned DHCP -- and a misbehaving DHCP client could certainly be the culprit.
In doing some of my own network investigating recently, I discovered that services like Suricata will (by default) take down network interfaces and restart them when they get new rules. I wonder if something software on your router is doing something similar: Are you running Suricata or Snort?
Also: Logs are your friend. If you have access, review the logs of your firewall / router / etc.
In doing some of my own network investigating recently, I discovered that services like Suricata will (by default) take down network interfaces and restart them when they get new rules. I wonder if something software on your router is doing something similar: Are you running Suricata or Snort?
Also: Logs are your friend. If you have access, review the logs of your firewall / router / etc.