VPN Issues with Packet Loss

HI All

I have 3 VPN’s setup and 2 of these are running great. The two which are working great use Firebox VPN gear and CISCO VPN Gear. The one which I am having issues with is using D-LINK VPN routers at each end.

The issue is :

When data is heavy the VPN falls over. I tested this by sending a 1000 byte packet over the VPN and get NO packet loss. But if i increase this to 1300 bytes I get about 70% packet loss.
This VPN was working fine for years until i changed my router to a MikroTik RB450G from PFSENSE software.

Any advise please, as this needs to be sorted asap.

There are several types of VPNs possible. Which one you are using?

I am using a ipsec vpn