While replicating, slave server randomly prints this error and disconnects from master:
[ERROR] Slave I/O: The slave I/O thread stops because a fatal error is encountered when it try to get the value of SERVER_ID variable from master. Error: , Error_code: 1159
[Note] Slave I/O thread exiting, read up to log 'mysql-bin.xxxxxx', position xxxxxx
Where error code 1159 is in fact ER_NET_READ_INTERRUPTED: Got timeout reading communication packets
Executing STOP SLAVE; START SLAVE; on the slave server resumes the replication without any problem. The slave server should reconnect automatically though, which doesn't happen.
I believe the issue is in mariadb-sources/sql/slave.cc
There is a function called is_network_error(), which checks if the given error is network related. It's missing a check for ER_NET_READ_INTERRUPTED. Patch is very trivial:
Then mariadb will know that it was network related error and will try to reconnect automatically.