In every case I’ve tracked on that issue, there has been a firewall / proxy blocking the traffic.
Generally the layer-4 firewall is configured to allow ‘http’ on tcp/52311, but also needs to allow ‘https’.
With the https getting blocked by firewall, the client/relay would normally fallback to using http instead, but that fallback to clear-text is not allowed since 'Secure Registration’s is turned on (and has been turned on by default for several years).
Talk with your firewall team and get https on 52311 enabled.