Help needed with openvpn and configuring as dhcp client

Hello, i planned to use my new wrt1200ac as vpn client with openvpn, but i got a few problems, everytime i cant setup a connection, i click on it and it does nothing. I followed this guide:

The second problem is that everytime i try to set the linksys as client under my main router, either via static ip or dhcp client, it cant apply the changes and "reverts back" to the old settings and i cant reach it anymore. I tried to directly connecting it or via my main router with cable. In the interface of the main router it just lists it as pc-192.168.x.x. and then i have to reset it to reach it again. SSH isnt working either.

Any help would be appreciated.

Hi, For your second problem, let's assume for now, there is no vpn config installed.
So you have 3 devices:

main router (openwrt?) <==> (yellow port) wrt1200ac (openwrt?) (blue port) <==> computer
'<==>' represents an ethernet cable

is that correct ?