@shberge hello. I have the same question. i couldn't make openvpn client works after upgrading the firmware of our ER7206 to the latest version 1.2.0 Build 20220117.
however "openvpn server" feature works well.

  @maratn 

It works well for me now, I also use 1.2.0. what i had to do was install OpenVPN Server with support for old clients. believe it was clients before 2.2.

Running VPN server on Ubuntu. you also need to create clients without passwords. tp-link does not currently support usernames and passwords.

when I had done this I have not had any problems except that it is very slow.

I'm not an expert on OpenVPN or Ubuntu so there was a lot of error and trial and error, but now it just works.

Since I am not an expert, I chose to use pivpn and run this on Ubuntu, it is simple and for dummies :-)

Then I can also run Omada SDN controller on the same Ubuntu machine.

  @GBenez Suggest you remove some parts of sensitive information because you are exposing your OpenVPN server info.