Winbox connecting over VPN: router has been disconnected

Hello,

I have this problem with every version of winbox.
SSH session keeps alive for a long time.

But winbox disconnects after few seconds, minutes, sometimes I cant even edit some value.

This problem happens only when I accessing router over vpn. If I connect to public internet IP it keeps alive for a day, two.

My network map to one of router:
Untitled Diagram (1).jpg

ssh connection keeps alive 5 days. Winbox connection still drops :frowning:.

What can be reason, that winbox drop, how can I debug it please?