@RCN_Sailor29 

How many devices are connected to C4000, wired, and wirelessly? You may optimize your wireless network, for the devices with small traffic, please connect them to the 2.4G network, like smart devices; for the devices with high traffic, please connect them to the 5G wireless network, like the smartphone/PC/TV, etc.

Feel the router top and bottom, how about the temperature? If it is what the environment should be, that should be normal. Ensure you put the router in a well-ventilated location or mount it vertically on a stand that permits the free flow of air, and use a fan to cool the router, a regular fan or USB fan is fine. As long as the router is not placed in an enclosed area then it should be fine. You can also try to set the Wi-Fi Transmit Power to low (if the setting is currently set to high), and see if this helps.

If none of these help, you may contact the local tech support to check the warranty cause the device might be faulty:
https://www.tp-link.com/en/support/contact-technical-support/#Hotline-Support