@masoly If you're talking about turning your MR600 into a VPN client, then it's not possible as NordVPN removed PPTP/IPSec support back in in 2018, and the MR600 uses PPTP as protocol.

Mind if I ask where are you located, just to check what is the latest firmware for your MR600 v2? (I'm just another user of the router) (in response to @IHaveThePower)

Just to verify, are you asking how to set up a captive portal on your TL-MR3020, with OpenWRT? If that's the case, the OpenWRT wiki has a list of guides here:...

You are welcome

This may sound like a dumb question for you. but: On your MR600, do you have QoS enabled?

@Danaphoria Can you try a combination of 3 bands (such as B3+B20+B32 or any other combination)? the reason for this suggestion is that from experience/observation, the MR600 works best with 3 or more...