The FIN 5.1.1-1 (Patch) is a patch to the initial 5.1.1 release that resolves the following BACnet issue. This is also the latest FIN version listed as BTL certified.
Updated code to remove the Virtual Port entry in case of FIN as a BACnet Client. Originally FIN was maintaining 2 port table entries (one physical and one virtual), which was creating ambiguity for the BACnet Stack and it was sending I-AM-ROUTER-TO-NETWORK. The Virtual Port entry is needed only in the case of when FIN is a BACnet Server.