Not all contacts are downloaded into iPhone from CardDAV-Server

I use server CardDAV for contacts

I have company and there is above 20 iPhones (5, 5s, 6) which used this CardDAV server

We have on server above 10000 contacts

On iOS 9.1 all contact on 20 devices sync correctly

After update to 9.2 or 9.2.1 contact are missing on devices and sync do not correctly, maybe 50 contacts

LINUX- DAVICAL 1.1.3.1