I have a Seagate USB 3.0 hard drive that I formatted while connected to my rMBP. I selected the Mac OS Extended (Journaled) format and GUID. Seemed to work fine connected to the rMBP. Even ran a TM backup to it. When I plugged the drive into the wireless router (Netgear R6250), I can see it from my rMBP and can read all of the files on it. However, I cannot write to the drive. I get an error message saying I don't have permission. Did I format it wrong? Is there a recommended format that I should use for a USB drive connected to the wireless router? Thanks!