Giitlab mirror push failed to connect

Hello,
We’re in the process to backup an old gitlab 12.8.5 (self hosted) to a new one 15.8.11

and I tried to enable push mirror old gitlab => new gitlab

OLD [docker container]

while attempting to sync::

“unable to access https://gitlab-new/puppetmodules/nmon.git… Failed to connect to https://gitlab-new/puppetmodules/nmon.git port 443”

NEW [ docker container]

Now, if I connect to 1st container (old gitlab server)

root@gitlab:/# git clone --bare https://XXX@gitlab/puppetmodules/nmon.git
Cloning into bare repository ‘nmon.git’…
Password for ‘https://XXX@gitlab-new’:
remote: Enumerating objects: 137, done.
remote: Counting objects: 100% (137/137), done.
remote: Compressing objects: 100% (68/68), done.
remote: Total 137 (delta 60), reused 124 (delta 52), pack-reused 0
Receiving objects: 100% (137/137), 648.25 KiB | 6.48 MiB/s, done.
Resolving deltas: 100% (60/60), done.
root@gitlab:/# cd nmon.git/

root@gitlab:/nmon.git# git push --mirror https://XXX@gitlab-new/puppetmodules/nmon.git
Password for ‘https://XXX@gitlab-new/’:
Enumerating objects: 137, done.
Counting objects: 100% (137/137), done.
Compressing objects: 100% (60/60), done.
Writing objects: 100% (137/137), 648.25 KiB | 216.08 MiB/s, done.
Total 137 (delta 60), reused 137 (delta 60), pack-reused 0
remote: Resolving deltas: 100% (60/60), done.
To https://gitlab-prd.itdprod.k8s.yacn.dk/puppetmodules/nmon.git

  • ced31a8…38b5273 master → master (forced update)

So, As you can see docker container is able to solve the URL + to connect to over https

But still on web interface I get unable to connect !!
Do I miss something, or ??!?