I have a Yealink phone at home that registers pjsip just fine, but I can’t access the UCP.
I have the UCP access as setup on local zone
under Admin > system admin > Port Management, UCP Secure Port is set to 4443, insecure is disabled.
When accessing UCP from an IP specifically listed in a trusted site, it works as desired i.e. https://FQDN/UCP
but from my house I must use https://FQDN:4443 to make it work, adding /UCP to the end makes it fail.