I suspect the rule is “do not block/filter 51111-51113”
Your situation is a bit more ‘edge case’ than most so you are going to have to experiment a bit. Strictly speaking this isn’t a VST connect issue but a firewall config issue.
Let us know if your test works - be interesting to see - and to see if we can up with solutions if it doesn’t
FWIW suspect video uses more standard ports that your firewall/router doesn’t care about which is why that part works.