webmail.domain.com site not working properly

Hello,

We use icewarp server software as in the versions below. The webmail.domain.com site is not responding after an average of 5 minutes after the webmail service starts working. After the service restart, webmail.domain.com opens, but after 5-10 minutes it still does not respond. There is no detail in the error logs. Can you help me?

Windows Server 2019 Standart

Deep Castle 2 Update 2 build 4
1859 Domains - 19520 Users