WDS of TL-WR941ND functions similar as repeater that both of them will extend the WIFI range, what's different is that repeater won't have another network while WDS will do.

:confused:Not so sure what you need to do... Maybe you can post some of the screen shots of your One-to-One NAT settings. By the way, have your configured any Loadbalance rules?

Is it WPA2-PSK or WPA2-enterprise? if it is the enterprise one, it seems TP-LINK router does not support WPA2 at all since there is no option for WPA2 on the WDS setup page. Maybe this is a...

I‘m not so sure about your settings on the TL-WR841ND. but you can find the configurating instruction on TP-LINK's FAQ: http://www.tp-link.com/en/article/?faqid=227, perhaps you can check your...

Restarting itself... Seems like it does not concerned much with the settings. I thought there may be something wrong with the modem itself.

Have you disabled the DHCP function on the TL-WR841ND? Seems your PCs have got IP address from the TP-LINK router.