I have two Asus RT-N16 units: one I bought many years ago, and another I bought earlier this week.
The one I bought earlier this week has "H/W Rev: A1" printed on both the box as well as the underside of the router (printed to the right of the PIN code), while my older unit doesn't have this printed anywhere. (If your unit doesn't have any hardware revision after the PIN code on the bottom, then it's probably a first-gen model)
I can tell something about this new hardware revision has changed quite drastically.
The most prominent thing I noticed:
The WAN port negotiates with my cable modem's port at 100mbit/full, not gigE speed. The RT-N16 box and manual (for the new unit) specifically state the WAN port is gigE. I haven't checked the behaviour when using the stock Asus firmware, but with TomatoUSB it definitely negotiates as 100mbit full. The issue is not with the Ethernet cable or the cable modem. Simply swapping RT-N16 units (same CAT6 cable) results in gigE speed using the older unit.
Are there any people here using an RT-N16 labelled "H/W Ver: A1" who can verify/confirm that they get gigE link negotiation on their WAN port when using TomatoUSB (any version)?
P.S. — I had written a *lot* more (including 2 other changes in the hardware, as well as speculating what the root cause is), except this bloody forum software insists I'm posting links when there isn't a single URL in my entire post. I'd include a URL to the actual original post I had written, except I can't include URLs, remember? Wonderful paradox.