Yealink W80DM registers with TCP but not UDP

I have a Yealink W80DM. I have connected 10 handsets and all register just fine with TCP. But, when I change the DM to UDP, registration fails every time.

I also have many Yealink T54W desk phones on site that work fine with TCP or UDP. It is just the W80DM giving me the issue.

I have checked the firewall for blocks, dropped the firewall temporarily, stopped fail2ban temporarily and no success getting it to connect via UDP

Any help regarding this issue would greatly be appreciated.

The issue was RPORT needed to be enabled on each handset in order to register via UDP. Rport was not necessary for TCP