Issues when enabling TLS for D785 on FreePBX

Hi there, I have setup my SNOM D785 desk phone for TLS encryption connected to FreePBX. The extension shows as registered on the phone. I can make calls from the desk phone no problem. When someone, whether an extension or external calls, the phone never rings and FreePBX is telling me that the device is offline apparently. I have verify client/server certificate disabled in FreePBX and I tested on the Zoiper android mobile app and everything works fine there - it's just the desk phone having issues. If I disable TLS and switch back to UDP, the phone works as expected. I'm not sure what else to try or configure. I'm using a LetsEncrypt certificate. Phone is behind NAT and using Wifi module. One more observation: when calling to an external number from the phone, as mentioned, it works but then when I hang up on the external phone... the desk phone still shows it's connected and never terminates. Any assistance is greatly appreciated!