SOHO router/modem devices [even half-way decent ones] do throw off quite a lot of heat and don’t last all that long for that reason, so best to lease at least the modem from your ISP, and let them deal with the problem, plus eliminates a ton of finger-pointing ...
also, make sure these devices have decent surrounding air circulation ... kiss of death [for the device and maybe even for yourself] to enclose in a drawer or a cabinet, or to fully engulf with books and crap ...
I buy my modems after too many failed ones that Time Warner gave me.
As far as SOHO goes for routers, the Orbi system has been great. Almost zero touch including periodic firmware updates and password changes I do every so often.
Yeah, if the device does not have thermal protection, and someone throws a blanket or pillow over it, it's a fire waiting to happen.