TP-Link TC-W7960 Throttling Internet Speed

What would be the first thing to check is that all your channels are locked down in your status page. If not, you will not be getting your max possible speed. You woudl also want to check your system logs to see if there are any critical 3 errors.

The critical 3 errors are the modem telling you that there is a issue with the internet signal. 

You need to contact the internet service provider, talk to a level 2 technician (a level 1 will just see you have internet and say its not them). Inform them that you do have internet, but you have constant drops, and see numerous critical 3 errors and would like them to clear those out.

To go back to the status page and the downstream and upstream channels. The value of power for downstream channels should be between -15dBmV and 15dBmV. If the value of power is not in that range, it means the line quality of that channel is not good. The value of power for upstream channels should be smaller than 50dBmV and the value would be between 30dBmV and 45dBmV normally. If the value of power is larger than 50dBmV, it means the line quality of that channel is not good. If there is 1 or more channels with bad line quality, the overall line quality may be bad.