Annoying Internet Problems

Randomly, I'll experience packet loss where web pages will take a lot longer to load, messages sent from chat services will be dropped, and games will lag. I have my Unifi gateway hooked up to the modem doing routine pings to several DNSs and it will show spikes in latency, packet loss, and outright disconnects where my gateway will failover to a backup 5G connection. Usually the speeds are fine but these hiccups get irritating when they happen daily. There's not really any pattern to the loss as in there's no time of day when it happens or specific usage that causes it, but it does happen almost daily. Restarting the modem doesn't make it go away.

I've already tried talking with support and after three times talking with a low-level tech, they finally sent a contractor out. The contractor didn't see anything majorly wrong and only grounded the connection to the outside box and recommended either to do a warranty replacement on the box or replace the modem that I've purchased. I went out of my way after trying warranty with Arris (they said there's a problem with the Xfinity line) to buy a CODA56 modem and the issues have not resolved. 

I've had my previous Arris S34 modem tell me frequently through the logs there was T3 disconnects or time synchronization issues. Sometimes there wasn't an issue with any connections otherwise but it would often happen during a logged event. There would also be a spike in correctable and uncorrectable packets on every channel (not just OFDMA). I haven't been able to check the Hitron CODA56 modem.

I'm at a loss. This has been going on since I upgraded to 2 Gb Internet 6 months ago and got the new Arris S34 modem with it for faster upload and download speeds and nobody has been able to see or fix the issue. I am convinced the problem is external.