Rsyslog Not Getting the Logs on Time

I have two central rsyslog server accepting UDP logs from multiple client machines.

Both are configured exactly the same.

For some reason, the 1st server doesn't get the logs from the client machines on time. I mean it will get it but delayed for about an hour or so.

The 2nd server gets the logs from the client machines on time.

As far as I can tell, there are no other process running on both servers and the loads are almost the same.

I know UDP is unreliable but I cannot figure why the 1st server is getting the logs but delayed but the 2nd server is getting it on time.