I never see this mentioned, however, if you are losing connection quality and "nothing has changed" you might want to check the following in addition to the fine recommendations made by sysop:
As a diagnostic tool, change the power outlet your router is using. Something else in the area may be deteriorating and causing electronic "noise" in the power line. If you are plugged into a line filter of some kind, bypass it and see if it has gone bad. Replace if necessary.
Test your router power supply for spec: Deteriorating or damaged power supplies can cause poor performance and/or disconnections. Residential power outages kill power supplies.
Heat is the enemy of routers. Blow out vent holes and ensure unimpeded air circulation completely around the router. If your router is "hot" to the touch, you need to address the cause.