I have a new build and getting ready to transfer big chunks of data over. I was planning on using rsync but this happens to the terminal window after a few seconds.

I originally thought it was because I had ad-blockers and anti-tracker plugins so I've disabled/whitelisted unraid on them. Happens both on edge and chrome.

Is the main GUI page still accessible? If so, go to Tools -> Diagnostics and attach the resulting zip file to your next post. I don't use Windows much or Edge at all. Is it trying to protect you from the threat it feels is posed by the unencrypted connection? Does clicking the "! Not Secure" message give you the opportunity to accept the risk and continue? There are other ways of accessing the Unraid terminal. A popular one for Windows is the free utility called PuTTY. That creates an encrypted connection of its own using ssh, without needing you to use a secure web connection.