If the domain has already been taken over with a transfer order, but it still shows the previous provider via the browser or no page can be reached, this is due to the fact that the name servers of the registry (domain issuing authority) have probably not yet been restarted and / or the name servers of the access provider (provider of your DSL / FTTH connection) do not yet have the new information of the domain.
During a domain transfer, transition periods of several days are possible before the domain points to the new account. However, experience shows that the name server information is already updated after 24 hours.
