Thanks.
I don’t seem to be making much progress. I’ve created and re-created what I BELIEVE will be an appropriate firewall rule. It’s here (takes a couple of screen shots as it scrolls off the page on the Unifi interface):
(I’ve obfuscated the middle part of the IPv6 address…)
For the IPv6 connection, the Roon ARC disgnostics still show:
“ipv6_connectivity": {“status”:“NetworkError”,“status_code”:504,“error”:“error: Error: ETIMEDOUT, response code: undefined, body: undefined connected? undefined”},
…
“external_ip”: {“actual_external_ip”:“159.ggg.hhh.iii”,“actual_external_ipv6”:“2403:aaa:bbb:ccc:ddd:eee:fff:aaa”,“router_external_ip”:“null”},
“natpmp_autoconfig”: {“status”:“NotFound”},
“upnp_autoconfig”: {“server_ip”:“192.168.0.1”,“found_upnp”:true,“error”:”<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/\" s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/\“><s:Body><s:Fault>s:ClientUPnPError<UPnPError xmlns="urn:schemas-upnp-org:control-1-0">718ConflictInMappingEntry</s:Fault></s:Body></s:Envelope>”}
}
Important (??) bits in bold. (I am not an IPv6 expert - you will have guessed that!)