OpenEVSE goes slow

My EVSE box has WiFi firmware 2.7.4 which has become progressively more sulky and now I need to power cycle the box to keep it running.

The symptoms are generally that it is very slow to respond but on the WiFi setup page it can only see the network it is connected to but if I power cycle it then it can see about 20 networks.

The image shows it in sulky mode. It responds to the Restart button but but very slowly. A fix only works if I walk to the garage and switch off the mains supply for 5 Seconds.

Any ideas?