They should not conflict with each other. Try to remove the network profile and reconnect on your wireless device. Wired connection is OK?

That's how you configure WDR4300 as an access point? http://forum.tp-link.com/showthread.php?78963-Can-someone-post-their-settings-config-file-for-Archer-c7-v2-as-an-AP&p=156734&viewfull=1#post156734...

Did you change channel on the main router and reconfigure the second router? Try to use the bridge router as the main router and test if it also disconnects. By the way, model number in the title is...

The router cannot boot up properly? It was working or it is brand new? Are you using the original power adapter?

Is it still under warranty?

Router and PS4 are on the same floor, right? It is okay to buy a range extender. Also, powerline extender kit may work as well. http://www.tp-link.com.my/products/network-expansion.html