TP-Link MR6400 with QMI over oVPN

Hello guys :slight_smile:

So far ive done two routing methods with I would like to combine.

First one: Archer C6U v1 that gets WAN connection from an LTE router via cable and redirects the LAN traffic through OpenVPN by adding a custom config file to it and changing firewall rules accordingly.

Second one: Installed OpenWRT on MR6400 v5.20 and used QMI to get cellular data.

My problem is that when I try to combine the two methods and use QMI + oVPN on the MR6400 alone, it works for a brief second and then something gets stuck and I cannot access the internet anymore as long as the VPN is up.

Can someone please explain to me what firewall rules need to be configured so my MR6400 will get WAN via QMI and pass it to the oVPN tunnel?

Thanks in advance