Gigabit Internet Slows After a While and Now Regularly Drops Internet Connection

I just upgraded to Gigabit on January 17th with a new Motorola 8600 modem and I have had problems ever since.  After I reboot the modem, the speed usually settles into 940 Mbps/41 Mbps but after a day or so drops down to about 150-200Mbps/41 Mbps.  The connection log shows a lot of correctable and uncorrectable errors on one particular channel (17 -- 483 Mhz) consistently through multiple reboots.  The signal and power levels also drop as I head into the lower frequencies with errors only on the lower frequencies.

I thought maybe the inside cable had an issue so I ran brand new RG6Q with compression connecters directly from the ground block outside (also replaced the ground block) to the modem.  No change.  I bypassed my router (ASUS RT-AC88U with latest Merlin FW) by connecting directly to the modem, not much difference.  I bypassed the entire inside of the house by connecting the modem directly to the outside drop with little difference.  The same channel shows lots of errors and low signal/power levels.

Today the log shows lots of errors (all correctable except for channel 17) across the board and today I started having the internet connection drop out for about 30 seconds a few times a hour.  No action on my part and it comes back.

I had an SB6183 with the same router on a 275Mbps tier and had very few problems for several years before I upgraded the service and the modem.

Any help would be appreciated.

Modem Connections 

Modem Error Log