I have installed my own sks-keyserver on debian 8.0 via repository and asked some peers.
When I start all sks-daemons, everything works fine and keys are synchronized with other peers.
Unfortunately, SKS stops listening on port 11370 after a while and the synchronisation stops. After restarting SKS, port 11370 is available again..
Neither the db.log nor the recon.log shows any log messages at that point.