Seems I’ve restarted something here 
I don’t think my unit dropping wifi is a signal issue as the AP is only a few feet from the EVSE.
Also, when it does drop the wifi it does not go into STA mode - it just becomes unresponsive and needs a power cycle to recover.
Are we sure there isn’t some interference in the EVSE disturbing/corrupting the ESP?
There is the potential for some RF interference inside the EVSE especially if the car’s electronics isn’t too well designed. Not to mention potential spikes at switch on/off.
Looking at my unit
The ESP power supply and Tx/Rx/Gnd wires are tied to the ct and earth cables. Maybe not the best route to minimise interference.
When I get a chance I’ll try segregating the ‘electronics’ cables from the ‘power cables’