Solved High lag on NordVPN - RT-AC86U

[cowst]

Hi,
in the latest couple of weeks, some time after I updated to latest Merlin after over an year (with factory reset), I noticed that when connected with nordVPN, the connection, beside being a little slower than without VPN (no surprise here), has a very high response time.
I noticed it because it started often to timeout on some requests, most visibly on kodi stream requests.
I never felt the need to investigate bad performance on vpn until now, so I cannot be sure it was great before, but the behavior in the attached picture doesn't seem right.
A similar behavior happens on my android tv (where I noticed it first), but also from my laptop, which passes the same tests with shining colors without vpn.
And I tried different servers, although the client should pick one currently good server by itself.
Do you have any advice to further troubleshoot?
I was hoping the issue is with some conflicting setting that I set when I upgraded the router, otherwise it means the issue is out of my control.

Thanks

 

[cowst]

Mystery solved.
Apparently with openvpn for android, having an old server config will result in a dns that is not the one expected with the vpn server nor the ones I tried to force in.
This arbitrary dns seems to be superslow and causing the reported issues.
A newer config to another server solved it.