nginx: [emerg] bind() to ["my old IPV6"]:443 failed (99: Cannot assign requested address)

I installed ISPConfig when my server had an IPV6 address, but now it can't.
When I test nginx start :
nginx -t
nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: [emerg] bind() to ["my old IPV6"]:443 failed (99: Cannot assign requested address)
nginx: configuration file /etc/nginx/nginx.conf test failed
So can anybody help me to start nginx please ?

 

I commented every vhost ipv6 references then nginx started after killed processus nginx because of multiple error 98.
I had already removed the ipv6 adresses in websites in IspConfig. Tried some saving also this time.
I erased the ipv6 server option in ISPCONFIG's last panel.
And finally... still unable to go to my sites. But right now I prefer reinstalling the whole thing.

 

Right now I reinstalled ISPConfig but it seems it can not connect with admin-admin login-passwd.

Code:

~$ systemctl status nginx.service
● nginx.service - A high performance web server and a reverse proxy server
   Loaded: loaded (/lib/systemd/system/nginx.service; enabled)
   Active: active (running) since mer. 2018-01-24 20:44:11 CET; 6min ago
  Process: 7065 ExecStop=/sbin/start-stop-daemon --quiet --stop --retry QUIT/5 --pidfile /run/nginx.pid (code=exited, status=0/SUCCESS)
  Process: 8367 ExecReload=/usr/sbin/nginx -g daemon on; master_process on; -s reload (code=exited, status=0/SUCCESS)
  Process: 7070 ExecStart=/usr/sbin/nginx -g daemon on; master_process on; (code=exited, status=0/SUCCESS)
  Process: 7067 ExecStartPre=/usr/sbin/nginx -t -q -g daemon on; master_process on; (code=exited, status=0/SUCCESS)
Main PID: 7071 (nginx)
   CGroup: /system.slice/nginx.service
           ├─7071 nginx: master process /usr/sbin/nginx -g daemon on; master_process on;
           ├─8370 nginx: worker process
           ├─8371 nginx: worker process
           ├─8372 nginx: worker process
           └─8373 nginx: worker process

 

you must use the admin-password from your setup. the default is not admin anymore.

 

And finally... still unable to go to my sites : I checked my sites from another network and it worked. So it brings me to the question why are my sites not accessibles from my own network connexion ?
When I had an IPv6 access to the server it was possible, so not any more.
Right now I am trying to configure the dns server part of ISPConfig if it can be a solution to access sites from my own connexion.
Or a router capable of that, with OpenWRT or DD-WRT which are able to inject custom domain-name to IP address resolves via their own internal Hosts files and/or internal bundled DNS Masquerading software such as DNSmasq..?
Or maybe resolve dns from the computer on which I do webmastering ?
Any ideas ?