Aspects of 2.4 & 5G WiFi. Connecting different devices in the home?

> 1 PC and 1 LED TV are connected directly to the C6300. [...]

   "directly" means by Ethernet cable, or what?  And how, exactly, is
the network interface on your (unspecified) "1 LED TV" configured?

> [...] Why is this happening and what is the fix?

   Based on not much information, my guess is that the network
configuration of your (unspecified) "1 LED TV" conflicts with that of
your router.  What does it say about its network configuration?

   I'd try resetting the TV, and letting it try to use DHCP to configure
itself.  The instructions for the TV might offer some clues.