If I file an IFR flight plan Toronto - Cleveland, Duats says "Flight
plan accepted by DynCorp IS DUAT service and will be filed with ZYZ
on..." YZY is Toronto Center. The same is true if I file Ottawa -
Toronto. In that case the flight plan is sent to ZUL (Montreal). So it
appears that the flight plans are handled seamlessly across both
countries for IFR.

However, if I file VFR Toronto - Cleveland, it says "Flight plan
accepted by DynCorp IS DUAT service and will be filed with ERROR on
...."

Obviously, Duats is unable to link with Canadian FSS services. Anyone
had experience using Duats in Canada?