Internet slows to 0.5Mbps, randomly and frequently throughout the day

I’ve been having an issue with my internet where it randomly becomes extremely slow multiple times throughout the day. Some days far worse than others to the point that it’s practically unusable. In these moments of slowness if I run a ping test to the first hop outside of my network on my trace route it takes upwards of 5000+ms round trip for sometimes 30 seconds and other times several minutes of this until it calms down and becomes somewhat fast again.

It started a couple weeks ago so the first thing I did was replace my customer owned cable modem with another brand new modem because my current modem was listed as ‘incompatable’.

This did not fix the problem.

I contacted tech support, they sent a technician to check the wiring (the modem is installed outside the house in a weatherproof enclosure 2 feet of cable away from the ground block because techs will not come inside).

The tech replaced all the cable ends and ran a speed test with his modem and it passed.

The problem continued (as it is intermittent and he didn’t catch it while he was here).

I then tried to get tech support to give me tier 2 support, on one of my many calls they did and they told me they saw 4,000ms latency while pinging the modem. The next time I called in I was told I couldn’t get tier 2 support unless I rented a modem as they would not diagnose trouble on a customer owned modem.

So I rented a modem (now my 3rd modem in a week). The problem persists.

I have tried connecting directly to the modem (without the router in between) with brand new computers, All hardwired, Even the connectivity test built into the xfinity modem fails, returning only 3 of 4 packets in the ping test when this problem manifests itself.

It seems it could be some sort of interference on the line that comes and goes throughout the day. Rebooting the modem seems to make it better sometimes and worse other times.

I’m at my wits end at this point and don’t know what to do, they sent two techs out the first replaced the connectors, the second just looked at what a nice job the first one did, but I believe it’s possibly an ingress problem because the signal levels (per the tech support folks) are all good - and since it’s intermittent I have a hard time getting someone on the phone while it’s still happening. I’ve spent 8 hours at least so far on hold and on the phone with tech support this week.