How to use TPLink WD8961ND to extend the Time Capsule

I have an old adsl wireless router TPLink WD8961ND, and now it is not used anymore. I am trying to use it again as another extended wireless with time capsule as the main wireless base.

You may not be aware that Apple uses proprietary settings for their "extend a wireless network" feature, which are designed to only allow other Apple devices to "extend" the network wirelessly.

So, while it might somehow be possible for the TP-Link device to do what you want.....it also very unlikely that it will be able to do what you want.

TPlink can act as a wireless bridge (using WDS), but does time capsule support WDS?

Apple dropped WDS support over 3 years ago. Even if WDS were still supported.......WDS operates at much slower "g" wireless speeds and uses obsolete security settings, so there would be no advantage to using these older settings, even if you could.

Unless you have tons of time on your hands to experiment, and a lot of patience as well, my advice would be drop the idea of having the TP-Link extend the network wirelessly......and look at a setup where the TP-Link is permanently connected to the Apple router using a wired Ethernet cable connection.