I am having an issue connecting to the server as the error I got was: Received empty response from Zabbix Agent at [198.204.xxx.xxx]. Assuming that agent dropped connection because of access permissions. Any ideas on what could be wrong?
The host is running Alma Linux 8.X and the Zabbix server is running Ubuntu 22.04

Thanks

So I did a debug and I got this error in the logs:

1492643:20240630:120612.045 zbx_setproctitle() title:’listener #7 [waiting for connection]’

1492645:20240630:120612.046 zbx_setproctitle() title:’listener #9 [waiting for connection]’

1492642:20240630:120612.047 zbx_setproctitle() title:’listener #6 [waiting for connection]’

1492644:20240630:120612.047 zbx_setproctitle() title:’listener #8 [waiting for connection]’

1492646:20240630:120612.047 zbx_setproctitle() title:’listener #10 [waiting for connection]’

1492647:20240630:120612.049 In send_buffer() host:’198.204.xxx.xxx’ port:10051 entries:0/100

1492647:20240630:120612.049 In format_metric_results()

1492647:20240630:120612.049 End of format_metric_results():FAIL

1492647:20240630:120612.049 End of send_buffer():SUCCEED

1492647:20240630:120612.049 zbx_setproctitle() title:’active checks #1 [idle 1 sec]’

1492636:20240630:120613.041 zbx_setproctitle() title:’collector [processing data]’

1492636:20240630:120613.041 In update_cpustats()

1492636:20240630:120613.042 End of update_cpustats()

1492636:20240630:120613.042 zbx_setproctitle() title:’collector [idle 1 sec]’

1492638:20240630:120613.045 zbx_setproctitle() title:’listener #2 [waiting for connection]’

1492637:20240630:120613.045 zbx_setproctitle() title:’listener #1 [waiting for connection]’

1492639:20240630:120613.045 zbx_setproctitle() title:’listener #3 [waiting for connection]’

1492640:20240630:120613.046 zbx_setproctitle() title:’listener #4 [waiting for connection]’

1492643:20240630:120613.046 zbx_setproctitle() title:’listener #7 [waiting for connection]’

1492641:20240630:120613.046 zbx_setproctitle() title:’listener #5 [waiting for connection]’

1492645:20240630:120613.047 zbx_setproctitle() title:’listener #9 [waiting for connection]’

1492642:20240630:120613.047 zbx_setproctitle() title:’listener #6 [waiting for connection]’

1492644:20240630:120613.048 zbx_setproctitle() title:’listener #8 [waiting for connection]’

1492646:20240630:120613.048 zbx_setproctitle() title:’listener #10 [waiting for connection]’

1492647:20240630:120613.049 In send_buffer() host:’198.204.xxx.xxx’ port:10051 entries:0/100

1492647:20240630:120613.049 In format_metric_results()

1492647:20240630:120613.049 End of format_metric_results():FAIL

1492647:20240630:120613.049 End of send_buffer():SUCCEED

1492647:20240630:120613.049 zbx_setproctitle() title:’active checks #1 [idle 1 sec]’

1492636:20240630:120614.042 zbx_setproctitle() title:’collector [processing data]’

So I have 3 other servers that work fine, but these 2 servers, one on another has the same issue a above.

The agent config file hostname and IP are set exactly and able to telnet so not a firewall issue.