No WDS bridge on TL-WR941HP. if you want to extend wifi signal, set range extender mode

It looks like you want the WISP or hotspot mode, available on TL-WR902AC

Do the access points and the main router use the same ssid? You may try them to different ssid to locate whether just one has the issue or all of them have the issue. The channel of the three device...

Like the modem or the PC/phone connected to the router. It is hard to say when there is a compatibility issue. Disconnect all of them then check the situation.

Did you follow the manual to do wifi clone? You may follow the instruction to do the clone, then the tp-link will have the same wifi name as your main router. http://uk.tp-link.com/faq-398.html...

V1 and V1.20 use different hardware. V1 can't use the firmware of V1.20. AV500 and AV600 are theoretical maximum throughput. AV500 should be enough if the bandwidth from internet provider is just...