Posting as the previous old thread https://community.tp-link.com/en/business/forum/topic/670808 was closed.

Has anyone manage to resolvet his as I have this on the newest firmware of 11.3 and seeing if this can be done via CLI? 

The Omada Controller doesnt offer the GRE Support (only standalone) and we still get this error. 

Thus, hoping this could be configured via the CLI or if anyone has done this to get it working.