Frontail URL resolves to IPv4 and IPv6 simultaneously

I’m using openhab3 on openhabian.
In the upper right corner of the openhab UI I can open additional APPS. There is also located the frontail log viewer. Clicking on the Icon opens the URL:
I replaced the correct numbers by x to focus on the magic part.
I.e. the IPv4 address is followed by the IPv6 address.

The config file /etc/openhab/services/dashboard.cgf contains the parameter{HOSTNAME}:9001

In the BASH the command
echo $HOSTNAME resolves to openHabian3

Ok I can hard core the correct URL in the dashboard.cfg but this is not as it should be.
Can someone tell me the secret to get the correct URL in the Link.

So what when it does the trick ?
There’s many ways, disabling IPv6 is another one of them.
See Wrong URL for Log Viewer when multihomed OH3 · Issue #872 · openhab/openhab-webui · GitHub

Unfortunately it doesn’t do the job. I hoped so.
So I check the like you gave me but none of the ways helped.

I have just one single network interface; I have deactivated IPv6 in the openHAB UI and change the dashboard.cfg to a fixed IP and I updated the openhabian with apt-get update / apt-get upgrade

But I found out, that the file runtime.cfg has another definition for the URL where the wrong URL was hard coded. There I changed it to the correct IPv4 and now it works.