Wifi strength

I have installed a ring door bell and chime in the home of an 87 year old friend.I have tried EE mini wifi and Vodafone’s mini wifi, both working off sim cards and the signal is too weak. Less than 0.5 meg upload.I checked with O2 and Virgin and they said theirs would not work either due to signal strength.I’ve asked all of them including BT what upload I would get from a wired modem and the best I can get is “up to” 1 Meg with BT.The wifi will only be used for the doorbell and will be situated inside, by the front door, about half a meter away from the bell. Will this be sufficient?