When you change it like here:

PyBitmessage stops the network using 'dontconnect' setting and listening port 8444 appears not available upon the following network start:
2021-06-01 20:21:07,051 - WARNING - Failed to bind on port 8444
2021-06-01 20:21:07,051 - WARNING - Setting port to 45311
It may be another source of the multiport hosts, which I'm trying to optimize in knownnodes-opt branch.