If Grey water watch does not receive ravens since it moves, how does the Reeds receive news of Westoros?

I am on a re-read and in one of Bran's Chapters Jojien explains how no one can find Grey water watch since it moves around, that also means that they do not receive ravens since they would not be able to find the Castle either.

How do the Reeds get news of Westoros if ravens are the primary source of communication?