I wanted to put this out there in case some other poor savage goes down this road. Plugging a Ziply fiber connection into a EdgeRouter 4 will most likely see you dropping packets randomly. This is due to the MTU size needing to be adjusted. In my case, the default value in use was 1500. I needed to set it to 1492 to eliminate the issue. I screwed around with numerous equipment swap outs and resets trying to figure out what was going on. I have had to set the MTU for an ISP exactly once in my life (this being it) and I have consulted for a great many years. I have a redundant Internet connection. The failures would see me ping ponging between connections (driving me insane in the process). The fix:
SSH into your router (or CLI in the GUI) and do the following:
set interfaces ethernet ethX pppoe X mtu 1492
set firewall options mss-clamp mss 1452
set firewall options mss-clamp interface-type all
Reboot your router and you should be good. You can also do this in the GUI. Select your WAN interface (via DASHBOARD tab) and click config. You will see the MTU value there. Next, you can go to config tree and then firewall / options / mss-clamp : Enable IPv4 TCP MSS clamping for specified interface types. Set the value of 1452. Save and reboot.
Hope this helps you!
Friday September 15, 2023