Web UI not available from new install on Ubuntu 18.04

pht-for-linux

#1

"Unable to connect

Firefox can’t establish a connection to the server at localhost:32400."

ThinkPad core i7 with 12Gb, Ubuntu Mate 18.04 64bit, Plexp 1.12.3.4973-215c28d86_amd64.

Any ideas anyone? TIA.