SIP behind DLink DI604 falls to sleep

Only outgoing calls after a while…

Both IP-phones and Sipura adapter works OK just after they are rebooted. When trying after 10 minutes you are only able to call out. When you try to call in either the IP-phone or the phone behind the Sipura rings.

Have the newest sw version in the SIP units and in the DLink.

Any suggestions?

Ole