Are the devices actually disconnecting from the wifi or is it a case that they are still connected to the wifi but the Internet connection is dropping? With numerous devices dropping at same time (especially close up), it could be in my opinion that you are losing Internet connection to the router.
Regarding low signal strength, the only option really is to position the router in a way that its not obstructed by walls and items. Repositioning the router in the house usually isn't an option due to the limited amount of coax cable you get.
Apart from that the only real viable options are pods from virgin, which I've never used so I can't recommend either good or bad, like previous posters have said ethernet cables which you have said is not an option, or spending money on a 3rd party router or mesh router system and putting the hub in modem mode.
It could also be that you have too many devices connected to 1 or both wifi channels and thus running out of channel bandwidth., which could be solved by splitting the wifi channels to 2.4g and 5g and assigning some devices to the 5g channel. Putting the devices what are like 2m away onto an ethernet connection might also reduce the wifi bandwidth usage.
In my house, my router is near my tv, so have tv, ps5, xbox series x and smart bulb hub plugged into ethernet for this reason.
Some people like powerlines, but for me they might be a stable connection but they don't give the speed that other options give. I think now with the mesh router systems, powerlines are obsolete.
I'd 1st make sure the Internet connection is stable 1st before anything else, if its not then it might need an engineer to come and look at it.
