Linux client 2.4.11 urbackupclientctl can't connect to urbackupclientbackend

I’ve tried the tailored installer provided from the server and also the generic shell script installer from
The urbackupclientbackend daemon is up and running:

root@asd:/usr/local/var/urbackup# systemctl status urbackupclientbackend
● urbackupclientbackend.service - UrBackup Client backend
     Loaded: loaded (/lib/systemd/system/urbackupclientbackend.service; enabled; vendor preset: enabled)
     Active: active (running) since Fri 2022-06-03 15:12:09 UTC; 10min ago
   Main PID: 46251 (urbackupclientb)
      Tasks: 12 (limit: 4698)
     Memory: 7.6M
        CPU: 1.670s
     CGroup: /system.slice/urbackupclientbackend.service
             └─46251 /usr/local/sbin/urbackupclientbackend --config /etc/default/urbackupclient --no-consoletime

Jun 03 15:12:09 asd systemd[1]: Started UrBackup Client backend.

it’s listening on port 35623:

root@asd:/usr/local/var/urbackup# ss -lnp | grep urb
tcp   LISTEN 0      4096                              *     users:(("urbackupclientb",pid=46251,fd=9))                      
tcp   LISTEN 0      4096                                          [::1]:35623               [::]:*     users:(("urbackupclientb",pid=46251,fd=10))

the backend is successfully connected to the server:

2022-05-29 00:15:29: Authed+capa for client 'asd' (encrypted-v2, token auth) - 1 spare connections

but urbackupclientctl cannot connect to the backend:

root@asd:/usr/local/var/urbackup# urbackupclientctl status                                                                                                                                                                                         
Error getting status 

it was caused by the firewall.