I’ve had a persistent issue over the past month or so as my primary LAN connection kept dropping its Internet connectivity – seemingly at random and with no real trigger that I could identify. What was even more perplexing to me was that my VLAN 20, which is connected to my PIA VPN, maintained its connection for the 22 days since the last reboot of my pfSense box.
For reference, I’m currently running pfSense 2.4.4.
In my system logs under Status > System Logs > System > Gateways, I noticed a repeated DCHP error entry, “sendto error: 55” – the process and full error looks something like “dpinger WANGW x.x.x.x: sendto error: 55.”
Whenever the Internet connection would drop, I could reestablish connectivity by physically unplugging the LAN cable from the pfSense box and plugging it back in.
There are a number of things that can cause this error to occur. In my case, however, it was a pretty innocuous issue narrowed down to the Monitor IP in the Gateway settings page. Go to System > Routing > Gateways and click the edit icon for your WAN.
I simply changed the Monitor IP (it’s blank by default) to Google’s server at 126.96.36.199 and the network hasn’t dropped since. (It’s been several days now – from what was dropping every few random hours.)
I have gateway monitoring turned off for my VPN VLAN connection, which may be why this is only affecting my default LAN going out over my public WAN connection. I haven’t seen anyone with this exact set of circumstances but I wanted to pass along my solution in case anyone else is pulling their hair out over it.