Ring Doorbell 3 plus wi-fi problems

So I bought a Ring 3 doorbell +; setup went fine but after fitting the bell outside connecting with my BT hub 5 hub wi-fi was sporadic with an RSSI reading of around 80 so I moved the bell & got an RSSI reading of around 60 but the bell still wouldn’t reliably stay connected to the hub wi-fi. Despite having no other wi-fi issues around the house, I bought the later BT hub 6, we don’t have fibre into the house but my speed is around 30-50 & 15-20 Mb/s. Went through the Bell set up process again but the RSSI reading has now gone up to 79. The bell does seem to connect more reliably but how on earth am I supposed to get an RSSI reading of 40 or better, it wasn’t even that with the bell, hub & phone all next to each other during set up. Thought about getting a Chime Pro, which is supposed to boost the signal, but at over £50, I just seem to be spending more & more cash on this thing with no guarantee it will ever work as it should, is this normal?