Numerous connection dropouts a day over several months

Basic info:

- Equiment was a rented XFinity X1 modem.

- Internet connection loss anywhere from 1 to 10+ times a day since late October/early November.

- Only manually reconnecting one or both ends of coaxial cable would restore the connection.

- Switched out rented modem with Motorola MB8600 modem + TP-Link Archer C9 router, connection losses somewhat less frequent and now auto-reconnect after a period of time.

 

Since October/November I have been experiencing internet connection outages multiple times a day. I discovered that reconnecting one or both ends of the coaxial cable between wall outlet and X1 modem would temporarily resolve issue, usually for a few hours until another outage would occur. XFinity status showed no area-specific outages near me, and my neighbor's public-facing XFinity wifi has worked properly throughout the entire time.

 

At some point in late November, disconnecting the coaxial cable no longer always resolved the issue, and sometimes I just had to wait it out. I decided to try another modem/router setup (MB8600 modem + TP-Link Archer C9) to eliminate the possibility of a failing X1 modem.

 

Connection issues are still present, usually 1-5 times every 2 days. I no longer have to reconnect the coaxial cable since the modem eventually reestablishes connection after a few minutes/hours.

 

I have seen similar forum threads that suggest looking at the down/upstream power levels and Tx/Rx, but I am unsure where to access these levels using the Archer C9 (I don't see any down/upstream diagnostics on the router page 192.168.0.1). Assistance would be greatly appreciated, since this has been an extremely inconveniencing issue that has only been bearable because of my neighbor's public xfinitywifi connection.