Hi there,
To be able to assist you fully, could you please answer the following questions:
1) Is there a firewall rule on the Check Point Open Server that allows the vendor host to initiate traffic?
2) Have you ruled out that there are no issues with the intermediary routers before the open server (by running a traceroute or pathping)?
3) What type of traffic have you attempted to send from the vendor host to the remote server 2?
4) What do the logs show? Could you attach a couple of screenshots?
5) Is NAT disabled on the VPN or not?
6) Can the vendor host communicate with any other nodes behind the SMB gateway?
Thanks.