Every time I run dump or backup command, I am getting the error "Failed RPC connection to the node ejabberd@node1: timeout"
When do the same from web interface - Err_empty_response
Server info ubuntu-16.04, 8GB, ejabberd-16.09, total users on node - 2100
It was backing up fine until now, no change has been made on the server. apart from the failed backup, ejabberd is running perfectly fine
2100 accounts is not too
2100 accounts is not too much, but maybe if they have very large rosters, or big vcards (with uncompressed images as avatars...)
In WebAdmin -> Nodes -> your node -> Database... you can view the Mnesia tables, the amount of elements and table size. Check if any of them looks suspicious to be abnormally big.
Otherwise, maybe backup/dump is not good enough to backup such a database. In that case, you can do a dirty backup: simply copy the mnesia spool dir, preferably when there is little activity in the server (at midnight).