Solved! Go to Solution.
I'll reply to myself as the fault wasn't with the TCP connection... Mostly.
The hardware wanted to read ascii characters so I had to take my string of hex characters, and translate it into ASCII characters and send that through.
This is an excellent tutorial to VISA based instrument control - https://labviewwiki.org/wiki/VIWeek_2020/Proper_way_to_communicate_over_serial