Manuel,
It appears that the default retry behavior changed in MPD 4.x, and the documentation is not entirely clear about it, but as it appears, the "set bundle disable noretry" option is now always required to get MPD to reconnect automatically after the connection has been dropped.
I've created a preliminary image (1.3b10-pre) with just this fix for you to try:
Thanks - I've had this 'failure to reconnect' problem for several days now (I assume since b8), I am in Ontario. I'll try b10 and see if things improve.
Peter