We have configured a Matrix-Synapse homeserver.
In Riot-Chat you can store all your encryption keys in a central backup:
Question: Where is this backup stored? On the homeserver? On the federation server? On the vector.im-Server? ... and (where) can I configure this (in the homeserver.yml)?
If I overlooked this information while searching the web, I would be thankfull for a link.
The encrypted keys are backed up (encrypted) on the home server: https://github.com/uhoreg/matrix-doc/blob/e2e_backup/proposals/1219-storing-megolm-keys-serverside.md