Setting Up Custom Email Server - Breaks Central

1. What is the problem? Be very detailed.
Can no longer log in after configuring custom mail server as per instructions. Get 'refresh the page' message due to being already logged in.

2. What app or server are you using and on what device and operating system? Include version numbers.

Docker Compose 1.29, Ubuntu 20.04.

3. What you have you tried to fix the problem?

Config as per instructions

4. What steps can we take to reproduce the problem?

5. Anything else we should know or have? If you have a test form or screenshots or logs, attach below.