Fleetspeak_frontend error: 'NoneType' object has no attribute 'Listen'

Environment
From release GRR Docker image.
GRR version 3.4.7.1
Ubuntu 22.04

Describe the issue
Fleetspeak fails to run. Admin UI works ok.

Error logs

2023-12-25T14:26:24.957692741Z Admin UI gui is at http://ubuntu:8000, clients will poll to http://ubuntu:8080
2023-12-25T14:26:26.849643948Z I1225 14:26:26.849372 139960087728128 server_logging.py:217] Writing log file to /GRRlog.txt
2023-12-25T14:26:26.934460548Z Traceback (most recent call last):
2023-12-25T14:26:26.934481417Z   File "/usr/share/grr-server/bin/grr_server", line 8, in <module>
2023-12-25T14:26:26.934624484Z     sys.exit(GrrServer())
2023-12-25T14:26:26.934691838Z   File "/usr/share/grr-server/lib/python3.10/site-packages/grr_response_server/distro_entry.py", line 26, in GrrServer
2023-12-25T14:26:26.934804227Z     app.run(grr_server.main)
2023-12-25T14:26:26.934810921Z   File "/usr/share/grr-server/lib/python3.10/site-packages/absl/app.py", line 308, in run
2023-12-25T14:26:26.934979308Z     _run_main(main, args)
2023-12-25T14:26:26.934985631Z   File "/usr/share/grr-server/lib/python3.10/site-packages/absl/app.py", line 254, in _run_main
2023-12-25T14:26:26.935129999Z     sys.exit(main(argv))
2023-12-25T14:26:26.935137301Z   File "/usr/share/grr-server/lib/python3.10/site-packages/grr_response_server/bin/grr_server.py", line 51, in main
2023-12-25T14:26:26.935254735Z     fleetspeak_frontend.main([argv])
2023-12-25T14:26:26.935261046Z   File "/usr/share/grr-server/lib/python3.10/site-packages/grr_response_server/bin/fleetspeak_frontend.py", line 44, in main
2023-12-25T14:26:26.935383398Z     fleetspeak_connector.CONN.Listen(fsd.Process)
2023-12-25T14:26:26.935454717Z AttributeError: 'NoneType' object has no attribute 'Listen'

Additional context
Command used to run docker container:
docker run --name grr-server --network host -e EXTERNAL_HOSTNAME=ubuntu -e ADMIN_PASSWORD=demo -e DISABLE_INTERNAL_MYSQL=true -e GRR_MYSQL_HOSTNAME=127.0.0.1 -e GRR_MYSQL_PASSWORD=password -d ghcr.io/google/grr:v3.4.7.1

No other services running on port 8080.