Hello.
I use IPsec/IKEv2 VPN. I set up the configuration according to this article. I also tried to add fast-track rules and rule changes MSS size. Also, I downed MTU to 1400 on the ether0 and local bridge (for LAN) But I get bad results in the speed test - 150/0.00. Also, pages load so very very slowly. I use NordVPN and in the mobile app using the same country destination, I get good results. But when I run a packet sniffer the internet connection works fine. Speedtest: 130/170. Pages be loading fast. How can I stabilize the internet connection without turning on the packet sniffer?
NO fasttracking of traffic going through the VPN tunnel. Drop MTU to 1280 or lower and see if the upload catches up.
If you are using RouterOS V7 then switch to WireGuard which is called NordLynx with NordVPN.
Use search in this forum and there are dozen of treads written about NordVPN.
PS. when you switch on the packet sniffer it will turn of fasttracking. So there is the your question, how.
Fastracking keep traffic away from the firewall lines/connection-tracking and it is directed from one point to the other point. This gives great speed but for encypted traffic it will also fly past decyption and so still encrypted and so, not readable.
When fastracking is on, some traffic is going the slow path each so many packets and those are the ones being also decrypted and giving you the impression that the connection slow and unresponsive. Slow traffic is needed to check if that traffic that is fastracked is still safe to be transported from one point to the other point.