Z-push - contact pictures make the connection loop

[Kordian]

Hello,
Here is my story: I have zimbra on a separate server. On another server installed z-push 2.3.9 with zimbra backend 67. Everything is working fine until the moment I add more than approx. 10 contact photos - then sooner or later everything stops working with various errors. Set the values for the contact photos to 15 MB, although they are rarely any bigger than 1 MB. Recently all ended with mobile loop error. Nothing other helps - wiping the device nor clearing the loops. The only solution is then delete the photos.
Any suggestions would be highly appreciated, thank you!
Regards

[Kordian]

Nobody can help on the subject???