No Agents Connected - Private Instance

I have been trying to set up a private WPT instance on EC2 with the installation scripts provided. I have successfully set up the server so I can see it in the browser, and the agent is polling for work, but I am still seeing “No Agents Connected” for my location on the /install page. I have tried following separate tutorials here and here but I get the same issue with both setups. This is what the access log is showing (internal server error): - - [05/Oct/2023:12:00:31 +0000] "GET /work/getwork.php?f=json&shards=1&reboot=1&servers=1&testinfo=1&location=localhost&pc=ip-172-31-85-47-<key-goes-here>&version=230405.214311&dns= HTTP/1.1" 500 5 "-" "wptagent"

Any ideas what I can do to fix this?