USB HDD on Netgear R7800 Transfer Speed Drops

So I just added a external USB 3.0 HDD to my R7800 router, running latest Kong Build. Have the drive setup using Samba (suppose that's the default on this as I don't see any other options).

Now when I do a few file transfers it starts out great... roughly 88MB/s, but then it will just drop to 0 for a few seconds, then shoot back up to 88MB/s again and continue.

Anyway to make this work better? I'm not expecting tons of speed considering this is USB 3.0 and all, but I would like consistent transfer rather than dropping on and off.

I'm wired from my PC to the Router btw

If running Kong, ask at Kongs.