This problem has sort of been covered but just want to state my exact problem. I Have the 211j and been running succesfully since mid March. Have it ethernet connected through DLink 2730B router to a wired connection PS3. Also have Linksys VoIP connection through the router.
Up until a few weeks ago the DiskStation would show up on the PS3 no problems. Last couple of weeks however it has started to 'disappear'. It will be fine for a day or 2 then can turn on the PS3 and its not there. Reboot the 211j and it is back fine. Can go into the DSM and reset the media server and it is fine again.
Thats ok but whole point of having a NAS for me anyway was not having to reboot everytime I want to view something. Not very wife friendly either when she trying to get the Wiggles running for the rugrat
I originally had DHCP enabled in router and it seemed to be dropping the lease to the NAS. Was set to default of 24 hours so I changed it to 150 hrs then to 1 and all had exact same issue. I have tried assigning Static IP's in router and still not working. I enable Dynamically getting IP in the DSM and also specifying a specific IP (with this set up in router also).
Have to stress it was working fine until few weeks ago. Have updated the DSM recently and insalled Window 7 updates as well. Latest firmware is on router.
Also have setup a Dynamic DNS and have all the DS apps downloaded onto Galaxy S which are all working fine.
Even tho the Media Server drops out the NAS is still available on Laptop and through DSM to move files about etc so it is still on the network and usable.
Any help would be muchly appreciated........
Alan

