Internet drops frequently during the day

I'm writing this on behalf of my client.

I've tried chat, I've tried calling, but it seems someone comes out, blames it on the modem, replaces it, and we still have problems.

I've tried to troubleshoot this as much on my end as possible.  My theory has been equipment overheating, just because this happens a lot in the afternoon.  I'm monitoring the IP addresses of the Comcast Modem, the default gateway of it, our public IP, a system that is pingable that is NOT behind our firewall and our firewall.  When we lose internet, we lose everything but the upstream gateway of the Comcast modem.  I use UptimeRobot.com to monitor the connection.

The cablemodem, again, just replaced Tuesday, is a Netgear.  Hardware version 1.04, firmware v3.01.15.

The signal levels, from the troubleshooting post on here, the only one out of spec is the upstream power level at 57.0 dBmV.

The network topology, again, let's forget about everything and focus on that internal IP address (from the 10.1.10.x range or even the WAN DHCP address, both of which don't respond to pings with the service goes down.  This has been ongoing for several months.  Sometimes it isn't as bad, again, this is why I was focusing on heat.

On a site visit the other day, the cable is run buried from the pole near the street to the building.  It looks to be standard RG6.  It also looks to be just inches from the top of the dirt.  During the heat of the day, the ground might be causing an issue.  I haven't found anyone else concerned with this, just concerned with replacing the modem.  So far, this hasn't helped. I understand there is construction costs involved, but I think this needs to be routed better to the building.

Is there any way to talk to someone that will do something other than replace the modem?  It was replaced Tuesday, and this is my findings from Wednesday:

Down at 12:35 pm up at 12:41 pm

Down at 2:47 pm up at 3:00 pm

Down at 3:07 pm up at 3:09 pm

Down at 3:50 pm up at 3:57 pm

Down at 4:01 pm up at 4:10 pm

Down at 4:13 pm up at 4:23 pm

Down at 4:36 pm up at 4:43 pm

Today:

Down at 2:27 pm up at 5:59 pm

Today was less outages, but it was down almost all afternoon.