We have a vendor that needs to connect to our on premise SQL Database for support. They just need access to the instance running, not the entire machine. So I setup a firewall rule that accepts connection from just their external facing IP address and NAT'd it to our private IP address that the server is hosted on. I only allowed traffic on TCP port 1433, since they just need access to SQL.
The vendor is able to connect just fine, but says the connection is really slow. Has anyone else setup a configuration similar to this with a vendor? Should I make any additional changes on the firewall? Or is the performance issue related to changes we need to make on the SQL Database? There is no issue when connecting to the database on premise, just when the vendor is connecting to it remotely.
Thanks in advance!