I tried Auto Channel and Channel 1,6,11 manually, there are 5 wireless routers in my area. I forgot to mention in my previous post, I have disconnect all of my 2.4GHz cordless phone too just to be safe. I did factory reset after the firmware upgrade then set it up from scratch, both of my router setting is exactly the same.
I just did one more test with my B1 earlier today, but still got the same result, I just don't understand why 2 router in the same place, same setting and same devices connected to it but still old one > new one.... here is what I got from my previous test:
With A3:
Laptop Wireless Status: 150Mbps
iPhone 4 : 11n @ 65Mbps
iPhone 5 : 11n @ 65Mbps
LAN Speed Test software: 9Mbps Down, 8Mbps Up
With B1:
Laptop Wireless Status: 65Mbps
iPhone 4 : 11n @ 65Mbps
iPhone 5 : 11g @ 65Mbps
LAN Speed Test software: 1.5-3Mbps Down, 0.7-1Mbps Up
Please help.....