Thanks for help!
I started every service that could have something to do with this issue, including remote registry, turned off firewall and also set value of AllowRemoteRPC key to 1 - this is solution to "Error 5 getting session names". Then tried to msg the computer from another one (did the remote registry, registry edit and firewall thing to both computers). It still gives me error 1825.
I'm using tomato firmware for router. Do you know any possible settings I should pay attention to?