Gateway doesn't start after upgrade from V8.4.90.1513_0+170 to V8.6.80.1018_0+152

I’ve upgrade from V8.4.90.1513_0+170 to V8.6.80.1018_0+152 and gateway doesn’t start any more with following error message in the log file

Sat Jun 16 17:38:20 2018: [kopano-gateway|T21728] [crit ] Unable to listen on port 993: Address family not supported by protocol

Pop3 and imap is disabled in the config file, only imaps is enabled. But SSL seems not to be the problem. Enabling only imap in config file (without imaps) results in error message

Sat Jun 16 17:38:20 2018: [kopano-gateway|T21728] [crit ] Unable to listen on port 143: Address family not supported by protocol

Any idea what’s going wrong here?

strace -e socket kopano-gateway -F