Upload Speed Issues

I've been having sporadic issues with my connection for the past 4-5 months, recently switched modems and still experiencing the same issue: drastic drops in upload speed at random intervals lasting anywhere from a few minutes to a few hours every day. I have tried resetting the modem multiple times to no avail. I am connected to the modem via router with an ethernet cable.

Speedtest during a bad hour

Speedtest during a good hour

Note the drastic difference in upload speeds: 3Mbps vs 16Mbps

I pulled the log from my modem (Netgear CM1100) below:

Any suggestions?