stick up cam has lost signal but door bell cam is working fine

i have had a few instances now where either one of my cameras or both lose signal and arent recording, or even showing on live view, i have checked on the app, it states they are connected and working fine.were having to switch off and on again to make it work, this is a problem because if were away from home this cant be done. it cant be related to any WIFI issues as some of the other cameras will be working fine and one wont work, and it also cant be to do with distance from the router as the ones further away will be working ten the one closest will stopthis cant be right, in my opinion this isnt fit for purpose for a security system, dos anyone else have these issues