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?