My hosting provider, if applicable, is OVH (host my domain name and proxies used).
Ports 80 and 443 are open in my router and forward them directly on my Synology. My firewall also contain rules to allow connections using ports 80 and 443.
So the problem is solved and came from port 80 who wasn’t redirecting correctly my IPv4 to my Synology (even if the rule was there and valid ?). Deleting the rule and recreating it worked instantly. Thanks for the quick responses and the efficiency guys.