Ermmm router have fans mini pc actually doesn’t( at least mine mines fanless) routers also fail to boot but also that not a giant issue either way cause who’s turning on and off their router and any significant interval I have run time of 6 months before mines restarted and that’s due to software updates otherwise it would push a whole year
Newer WiFi 6 routers tend to have fans cause they get fairly warm but I’ve had a ups on mine for literally years and had to replace the battery in it once but before I got one even I still never had that problem we haven’t had a power outage in like a year or 2 now and I maybe happens once a year if it does so I don’t see your problem and I have it set to auto turn back on when it gets ac power so it’s a non issue