Ring Pro loses Wi-Fi after a few minutes

Installed my ring pro last night and managed to get it working but went offline after about 5mins. It won’t reconnect automatically and I’ve reconnected it well over a dozen times and each time it goes offline between a few minutes up to 10minutes. Transformer was 4039mv and Wi-Fi signal is good. Have Virgin Hub 3 with a BT Home Wi-Fi system around the house to boost the signal. Don’t have the pro power kit installed. Took the guts out my old Deta doorbell, wired the transformer and then it’s wired direct to the Ring Pro using the blue/white and orange/white cabling. Any ideas before I revert to the old bell? Thanks in advance