ITC 308 WiFi - not reading temp correctly or connecting to WFi

My unit has lost connection to WFi and won’t reconnect and, it is not reading tje temperature correctly. The last couple of days it has been alarming to say it is over temp (just put this down to tje high ambient temt for the last couple of afternoons) however, checked ot this morning and it told me that tje tank temp was 118 F !! Put a standard thermometer in and that read 74F.

The unit is only a couple of years old, any ideas what is going on and how to fix ot?