Roon ARC no longer connecting

Hi - my Roon ARC is no longer connecting to my Roon Core - how do I fix this…?

Diagnostics as below;

“connectivity”: {“status”:“NetworkError”,“status_code”:502,“error”:“error: Error: connect EHOSTUNREACH, response code: undefined, body: undefined”},
“external_ip”: {“actual_external_ip”:“”,“router_external_ip”:“null”},
“natpmp_autoconfig”: {“status”:“NotFound”},
“upnp_autoconfig”: {“server_ip”:“”,“found_upnp”:true,“error”:“<s:Envelope xmlns:s="\” s:encodingStyle="\“><s:Body><s:Fault>s:ClientUPnPError<UPnPError xmlns="urn:schemas-upnp-org:control-1-0">718ConflictInMappingEntry</s:Fault></s:Body></s:Envelope>”}

This error message refers to a conflict in use of the same port between uPNP and a manual port forwarding rule. Probably solved when you either disable uPNP or remove the specific port forwarding rule.
Did you change something in the settings there? Or perhaps Roon Core shifted to another port number you previously configured a port forwarding rule for?

Thank you for your input, been scratching my head with this problem for over a week.