I'm using retropi v3.0 and I'm transferring my roms over via the local wifi. I am using a wifi stick that works in my older Pi Model B and after a certain amount of files transferred or time or something, it stops transferring in filezilla and slows right down. Fillezilla will generally say something about 20 seconds of inactivity and that software aborted the transfer. Right now it's reconnected itself and it's transferring at 5.6 KB/s. I could see this being a power issue, and I'm using a 1.8 amp phone charging(the one that came with my G4). If you need anymore info just ask and I'll go find it and post it.