So as an update, I disabled TCP in Asterisk SIP Settings and the errors above stopped. We do use an obscure TCP port for most of our NAT’d endpoints, but not on this server, so I was able to disable it. We have other servers with this setting enabled though, with no problems.
I read somewhere that since the GUI added the “yes, no” option for Enable TCP, instead of having to add it manually with tcpenable=yes, there may have been a double entry of the TCP enable, thus causing the error. Still to be proven though.