I've two kamailio servers sharing dlg vars between them and I've noticed that during high call load (~50-70 CPS) the kamailio that is processing all the calls and sharing the dialogs with the other kamailio, stops processing SIP.
If I set the parameter enable_dmq to 0 I cannot replicate the issue so I assume that it's related to dialog replication through DMQ.
Kamailio version: 5.4.7 - I've tested with recent versions but the issue remains