POL - 3001/4001

Solutions

This is usually a port in use error. Try rebooting your PC. Further steps may involve your firewall.

"Found the problem. Restarted router and cleared up a port issue."

It has been reported that the steps suggested in POL - 3101/3100 fix this issue.

Try connecting with ethernet cable rather than wifi. A discord user reported that rebooting their router without a SIM card fixed their issue (TMobile home internet).