I have a WRT160N V3. I'm getting 10Mbps from the wired connection and when I bypass it I get 18Mbps (what I pay for). The strange thing is that when I update the firmware or reset configurations it gives me the whole 18Mbps, but as soon as I start to make more tests it drops to 10Mbps.
I installed the dd-wrt custom firmware and it happened again, first 18, then 10. I thought that after some time the cpu or memory could be heavily loaded but dd-wrt shows me that the cpu load is always at 10% and used memory is 40%.
Tried to switch cables. Having exactly the same problem with a WRT54G V8.
Is there something to do with the Router <-> Analog Telephone Adaptor connection?
My current firmware is DD-WRT v24-sp2 (01/02/10) mini - build 13575M NEWD-2 K2.6 Eko.
---- UPDATE ---
I tested the router using IPerf with 2 wired computers and got 80Mbps.