2 solutions Solution 1-Flash DD-WRT your 830 Use WA801NDv1 files for updates, build r19342 read http://www.dd-wrt.com/phpBB2/viewtopic.php?p=695273#695273 Some official firmware of TP-LINK products...

NLOS penetration is dependent on two main items: type of Fresnel Zone obstruction (trees act different than building and mountains) -and- frequency of operation.

look yourself, click on top Tp-Link Home/Support/third line/Tp.Link Emulators, select 5110 to see 5210 and selext 7210, and you gonna see the dif. or click here...

as issues arise, my best recommendation unplug it for 10 seconds and plug to current every 3 days, it will works flawless

I don't see why disable wi-fi Simon answered on post 2, can't help you with Repeater mode, have never used but the how to here http://www.tp-link.com/en/article/?faqid=151 ignore model tutos are...

use same SSID and same security and passwords, but that would not make a dif. this toys wont let you do roaming, example, with a Iphone, 3 floor home, you are on floor 3, getting signal from a 5110...