I've searched all over the forums, and can find some similar questions, but no real answers, so here goes...
I have a Linksys WRT610N router (with DD-WRT firmware) acting as a WAP for most of my hardware (XBox 360, Macbook Air, assorted iOS devices, etc). It also has two hard wired connections - a 2010 Mac Mini HTPC (latest OSX version) and a new Synology DS413J NAS (latest DSM version). The router shows a gigabit connection, as do the NAS and HTPC. Main cable run is Cat 6 (approx 20m), with patch cables assorted Cat 5/5e/6.
My aim is to increase the file transfer rate between the HTPC and NAS. File streaming for Plex, music etc is fine, but large file transfers eg. copying a 5-10GB file, seem to run very slowly - occasional peaks of 60-80Mbps, but typically 3-5 Mbps at best. The HTPC and NAS both show low usage of CPU, RAM etc (using OEM tools to monitor during file transfer). The NAS and drives are brand new, with NAS specific 7200RPM drives, and the HTPC has a 120GB SSD and 8GB RAM.
Because the HTPC and NAS hardware seem to be barely running above idle during these file transfers, I'm guessing the problem lies in between. I can change the MTU in the HTPC and NAS to support jumbo frames, but the router MTU can't go above 1500.
1. Should I find a newer/better gigabit switch that supports jumbo frames, and just use the WRT610N as a WAP?
2. Will changing the MTU make a useful difference?
2. Should I buy new Cat 6 patch cables?
3. Any other tests I should run, or configuration changes I should make?