set a static IP Address on your computer so your computers LAN IP Address doesn't change
https://www.winmxworld.com/tutorials/static_ip.html - if you do it following those instructions then you must do it for every computer on the network because those instructions tell you how to do it in a way that will conflict with the automatic IP Addressing
then forward in the router to there, if your router is actually losing the port forwarding then it may be that you aren't saving the settings in the router, some routers will let you add a port forwarding that works straight away, but won't actually save it until you click save - so looks for a save (or save and restart) button in the router config
and a UPS for the computer is a very good idea, because routers don't care about having their power suddenly turned off, TVs don't mind having the power suddenly turned off, but computers really don't do well if the power dies in the middle of writing some important system file... files being corrupted all the time is likely to cause serious problems if you just let it keep doing it without getting it sorted out, and you just know that the day when your system refuses to boot up because of it will be the day you are running late and just need to quickly get that important presentation...