Daily signal degradations at night

I use a router, but modem is hardwired to the router and router is hardwired to PC.  I do not notice any amps on the line in any places, just a section on the outside where the grounding wire is, and the filter that is in place due to me having contour service as well.  I will not attempt to remove that since the filter is Cox’s.  In fact I think there is some sort of attenuator on the line because I did try to remove that when troubleshooting along with the splitters, but with that part removed, my SNR levels did not change, but my downstream power levels shot up out of this world to 19 point something which I know would be super DUPER out of spec, so I had to leave that on there.