Just for your information,
I modified line 1599 in /var/www/imscp/gui/library/Functions/Shared.php
It seems that $_SERVER['HTTP_HOST'] returns w00.mydomain.com4443 and this is not the result we expect. I don't know why the result is not w00.mydomain.com:4443
So I choosed SERVER_NAME as preference...
Now the panel is working again as expected.