Hello, this is widely discussed in the ubiquity Forum [1] because it breakes the UniFi Controller.
Consensus seems to be that the kernel upgrade with the fix for CVE-2017-1000364
caused the issue.
Strech seems to be affected as well.
Cheers,
Martin
[1]
https://community.ubnt.com/t5/UniFi-Wireless/Unifi-Controller-on-Debian-9/td-p/1967180
