Time to get technical

Ok, time for some thinking. Recently, after a replacement Siligence modem/router, the same issues of the modem/router doing random shutdowns due to "suspected power cycle" have started. The worst one came shortly after a reset of the modem due to wifi speeds going to below WiFi4 level, there's no specific time, no specific reason, it just drops at random at any time of the day or night. 

Putting a hand on the modem and you feel it's rather warm despite it being on the wall in the open, not enclosed, good air circulation.

This has me suspecting it may be "overheating" from time to time, irrespective of how intensive the use is, and I don't feel like pulling the power every night to let things rest.

So the question is simple. If I put the Siligence into "bridge mode", disabling wireless and everything except the WAN and one LAN port, will that help with temperatures and possibly the random shutdowns, while putting everything else through a new WiFi 6 router. I'm looking at solutions because this replacement started the same problems as the original one within weeks of installation, and they are increasing in frequency. Orange won't give me a newer model of modem, not even with the upgrade to Zen Fibre, and another SIligence will only end up doing the same again.

So, could this help solve what seems to be an inherent problem with the modem as it heats up if most of its hardware is disabled in bridge mode?