SIP peers falling down

Hello, the issue with Asterisk 13.7.2 happened about a month ago.
For unknown reasons periodically (2-5 days) all SIPs falling down and cant connect again. Restart Asterisk service doesnt help at all. Only kill Asterisk process or reboot.
All peers are static, so realtime we not using, but using AMI.
Maybe anyone had this problem and know how to solve it?