Three things not mentioned to check:
Plug in your power supply to a totally different electrical circuit (as a diagnostic tool). Electrical noise from a motor/etc could be causing your router to malfunction.
Do full diagnosis on your power supply. They do deteriorate, especially when restarting after blackouts and brownouts.
CLEAN all dust from your router and do anything necessary to guarantee lots of air flow. Internal overheating of your router can cause the symptoms that you are suffering. If your router is HOT to the touch, you must address the cause. Routers normally get warm, but HOT means potential trouble.