I have not had a piece of computer related equipment ever last beyond 4-5 years. On my third wireless router in the last 10 years here. Like yours they will be working one minute and causing wierd errors the next. Also like you, I have wasted quite a bit of time trying to find the issue before just replacing as a last resort. Starting to think the last resort should be the first priority in trouble shooting, but that kind of goes against the grain of us engineer/mechanic types.