V8.0.12 Gateway to V7.9.14 Issue

I have a Gateway Network outgoing from V8.0.12 machine to a V7.9.12 machine

The V8 machine was upgraded today, and I cant seem to get the data to come through. Connection establishes, and then no data materialises.

This connection was running and functioning before, when server was still on 7.9.14.
There is also another gateway network that is functioning as before, from the same V8 machine.

Any ideas please