I receive the above-mentioned error after installing Kolab on a fresh buster server, in accordance to the kolab online guide.
I fugured, that the problem is caused by the configuration during the kolab installation process.
netstat -tnlp | grep :143
shows a configuration only for tcp6. Tcp doesn’t even show up for the configuration process. The same is for all other ports except http and https.
I tried to globally deactivate ipv6 with the following commands:
net.ipv6.conf.all.disable_ipv6 = 1
unfortunately no changes. Could anyone give me some support please.
Thanks in advanced for your support!