RESOLVED REASON UNKNOWN- WiFi Pro XR Lite now not responding

Configuration:

  • PR60-1_R85PL Pro XR Lite 8 relay board
  • PR55-22 Wifi module
  • Has been working for 3 months
  • 3 other same configuration beside it are still working
  • Ubiquiti AP says it’s connected at -57db = good

Problem with the one board:

  • Responds to ping 50-150ms, ok
  • Commands which have worked (& used 1x/minute continuously), now “ERR_EMPTY_RESPONSE”
  • HTTP access to it 192.168.2.xxx - also “ERR_EMPTY_RESPONSE”
  • All 3 others respond correctly to those accesses
  • Have done “reconnect” on the AP to it, still bad response
  • NCD Base sees it, but then:
    image

These are on a roof controlling HVAC equipment. It would be very embarrassing to have to go there physically, the customer would know there’s a failure.
Any hope a power cycle would fix it? Even that would expose the failure.

Suggestions?
Thank you.

It has suddenly started working. No idea why. Leaving the topic for future reference, marking resolved.