Well, my 2Tb drive fails to be detected by the router so I don't know for sure if the 865L supports 1Tb as I don't have that size drive available to test out. I presume at the moment that 500Gb may be max. I found a problem with the 865L, after I dis-connected the 250Gb drive and connected the 2Tb drive, the 250Gb drive was still be listed in the Storage section on the routers page. I could only get rid of that listing by doing a factory reset on the router. I passed this info on to D-Link and also asked then what is officially supported on this model router. I'll post back if I get some info.
