I recently picked up a new RT-N16 (H/W version A1, firmware 126.96.36.199.276) with the intent of installing the Toastman firmware so that I could track down high network usage at the IP level. I upgraded the router to the latest firmware (RT-N16_188.8.131.52_376_2678-gb2dcaa5.trx) after doing an initial configuration (only way I could get access to the administration menus). I had a lot of trouble getting into Rescue mode - the Power light would not flash slowly if the Ethernet cable was connected. I could get into Rescue mode if the Ethernet cable was unplugged but plugging in the Ethernet cable caused the power light to either go off or stay on solid. The solution was to do a factory reset via the Asus administrative menus.
I initially flashed tomato-K26-1.28.7506.3MIPSR2Toastman-RT-VLAN-Std.trx to the router. The router seems to boot (power light and WiFi light on, LAN light flickering) but I could not connect to the 192.168.1.1 address from my Ethernet adapter at 192.168.1.10. Doing a factory reset (hold Restore button for 5 seconds, unplug, wait 5 seconds, power up router) did not help. In fact, holding down the Restore button did not seem to do anything (it caused the Power light to flash at a medium rate when the Asus firmware was installed).
I was able to flash the latest Asus firmware and PING 192.168.1.1 but could not connect on port 80. Port 443 was open but none of the usual usernames/passwords worked. This sounded similar to the problem reported in these forums on November 7/2014 ("Help with failed firmware update"). The solution was to do a factory reset, suggesting that the firmware upgrade is not clearing configuration information.
I tried flashing older, non-VLAN firmware Toastman firmware (tomato-K26-1.28.7505.2MIPSR2Toastman-RT-Std.trx) but still could not reach 192.168.1.1. Some posts suggested trying 192.168.0.1 but that didn't work either.
I was not able to get into Rescue mode after the second attempt at installing the Toastman firmware. Factory resets did not help (again, Power light stayed on solid). However, holding down the WPS button while powering up the router (based various comments in "What if you bricked your RT-N16 with a firmware upgrade?") got around that problem.
At this point I have restored the RT-N16 to the most recent Asus firmware. Am I dealing with a problematic router that needs to be replaced, should I be trying earlier versions of the Toastman firmware or should I learn to live with the Asus firmware?