OpenVPN unstable?

Hi. I’m using one OpenVPN tunnel, both server and client are using Mikrotik.
I’m connect with username and password, don’t use certificate.
But VPN is not stable.
Sometimes it’s still connect but it’s take me 5-7s to connect to any website.
That is OpenVPN in ROS issues or just openvpn issues? Should I use PPTP or L2TP instead?