so far after so many combination i try since afternoon 1pm my V2 arrive with poslaju,

best combo so far :

Panel ->  ZTE MF680 ->  TL-MR3420 V1 ( openwrt ) -> lan cable -> TL-MR3420 V2 -> wifi/lan to computer/laptop/phone wifi,

wireless G or wireless N in TL_MR3420 V2 is totally fine, 0% bug at all

but one thing i notice that, due to i test a few combination just now, so need to plug / unplug usb modem often a few time,

after a while the V2 become    able to recogise as fast as reboot done 100% but not able to dial the connection,...

i did upgrade from TL-MR3420_V2_120703 ( original firmware come with it ) to -> TL-MR3420_V2_120905

So now i will revert it back to try TL-MR3420_V2_120703  whether will be become    buggy or not after a few time plug/unplug,..

for my V1 with openwrt, this issue didnt happen at all, i can plug/unplug as many time as i want and it will still recognize fast and dial connection fast,..
the V2 can recognize your usb modem in one second after reboot 100% complete and dial the connection in next seconds in normal condition ,