@ginger1984 Some sites and apps only let you connect if you use their domain names. Also htttps, subdomains, etc usually imply the use of a domain name.

Connection to the router works fine.

This all is a bit hard to understand, but looks like you are accessing your local sites by IP? You could create entry in hosts file, associating your IP with some DNS name (better would be use DNS itself - routers should be able to assign some name for itself and other devices) and access your sites by this name and configure Opera for this name. If your IP changes, you only have to reassociate it in hosts file (or in DNS service).