Hello, this problem happens to me, sorry for the translation.
I have a tunne with wireguard between home and company, I have Mikrotik with 2 wan home side, the problem is this, when the 2 wan are on and wireguard connects with the Wan2 (Sky-WiFi) the tunnel tunged, from home I can pingare All the company on the company, but when you open RDP it opens up and remains black, after a while it gives me an error.
If I open the web page of the equipment, the link opens and remains there with a white page. If, on the other hand, the Wan2 disabled, and I only go out with the Wan1, RDP and the equipment web page works perfectly.
In my opinion I don’t think it’s a problem of rules, but I have been working on it without results for days.
If someone has the same problem and could help me.
Is there the possibility of deciding which WAN must go out wireguard?
Search for policy routing - RouterOS does not automatically send a response packet through the same interface through which the request packet came. You may want to read this.
But your description of what happens resembles rather some MTU related issues.
Thanks for the help, I followed this post and glued the rule, now it works.
http://forum.mikrotik.com/t/how-to-debug-mtu-size/116296/1