Solved by allowing gateway access
Please don’t overwrite your original post and say you solved it. Leave the first post there and add a separate post saying exactly what you did to allow gateway access.
That way if someone has a similar issue in the future, they would be able to fix it by reading your thread.
This community is about both giving and taking, and that includes sharing your knowledge when you learn something.
i. The solution was basically “check that your firewall rules are in the right order before posting”. My “Gateway” group was missing the relevant address, so it was nothing to do with echo, NC or port 8000. Whilst there is some learning here, it wasn’t HA specific, so I tried to delete my post. When I couldn’t I edited it. You’re right. I should have 'fessed up. Next time …