How to get maximum performance in a mixed 10/100/1000 lan

I have a question that I need advise on.

I recently bought an Asus RT-N16 wifi router with gigabit lan capability. I bought it for 3 reasons.

1. Gigabit lan capability.
2. USB connected storage sharing.
3. USB connected 3G/4G internet connectivity when wired lan fails.

I have 3 PCs with gigabit Ethernet on board. The fourth one has a 100 mbps Ethernet.

Now the question is this. Do all the connected PCs have to have Gigabit Ethernet capabilities to get such speeds or should I get this high speed connectivity between complying PCs?

For large file transfers I used to get around 11 to 12 MB transfer rate with a 10/100 ZTE modem /switch / router. This is like saturated 100 mbps connectivity. I am not getting anything close to this with the new router.

Any and all suggestions / advise is welcome and would be very much appreciated.

Pmshaw:

"Now the question is this. Do all the connected PCs have to have Gigabit Ethernet capabilities to get such speeds or should I get this high speed connectivity between complying PCs?"

Normally each machine will communicate at the highest speed that is available on that machines network card. Mixing 10/100/1000 network speeds don't have any bad effect. If the 100mbps machine is transferring files to a 1000mbps machine the speed is at the slower rate.

Rich