A TP-Link TL-WR841N router has been connected with another TP-Link TL-WR845N router in WDS mode. TL-WR845N is root router here, that means it's connected to the ISP. And secondary router TL-WR841N is configured for WPS connection as described here – http://www.tp-link.com/us/faq-227.html. Actually the main intention is using the second router as repeater of root router. But the problem is if any of the router reboots, then the secondary router (which is configured to WDS) can't connect to the root router; that means WDS connection has broken and without re-configuring, it will not work. It's a very boring task to configure WDS every time if any of the router restarts. Even if I have mentioned two specific model of TP-Link router here, but actually this scenario happens pretty much most of the TP-Link routers – that after rebooting WDS connection can't reconntect automatically.
Networking – WDS connection can’t recover automaticallly after rebooting router
routerwdswifi-configurationwireless-networkingwireless-router
Best Answer
Here is the full solution that worked for me with a TP-Link router, for completeness - step 1 was already posted in the comments, but it may not be obvious to everyone that it can be fixed without a factory reset:
Note: this problem and solution is independent of which router you are using for the primary router - my primary router is not a TP-Link router.