Modem/Router connection occasionally fails when the PC is connected

[WolfTeeth]

Hi Tom's Hardware Community,

I've had consistent issues recently with my network set up. The modem/router would drop any communication with each other and would provide a "WAN port is unplugged!" notification within the router's web interface. I have troubleshot with TP-Link's FAQ, Comcast's customer service, TP-Link's customer service, and Arris's customer service without any success. TP-Link provided me an RMA which did not fix the problem.

Searching through several different forums, I found a band-aid solution to my problem. A user with brown-out issues noted that they had success power-cycling the modem and router without any connections to the router (wifi and ethernet). While this works to fix the initial problem, the connection eventually fails. Testing whether I could have a functional network without having to unplug the ethernet cable or turn off the wifi before power-cycling, I found that the network would stay in place if I did not have my PC connected to the router via ethernet.

Firmware/updates have been made to the modem, router, and PC.
Connections made directly by ethernet to the modem function.
Failed connections result in a lost of the "Link/Activity" light on the modem while still retaining internet connection. The router loses internet connectivity during this time.
MAC address on the router is currently cloned to a laptop that initially was used in ISP set up per several troubleshooting FAQs.

Is there a more permanent solution to this problem? What methods can I use to determine is real issue?

Thank you

---
Modem: Arris Surfboard SB6141
Router: TP-Link AC1200
Laptop: Macbook Pro 13-inch Late 2011
PC Motherboard: ASUS m5a97 r2.0
PC OS: Windows 10 64-bit
ISP: Comcast Cable
Router Connections: 3 Wireless devices, 1 ethernet connection

 

[Ralston18]

Unclone the laptop as the first step. May being looked at as a router (which it is not) and causing network confusion.

Try another known working ethernet Cat 5e cable between the Arris and the TP-Link router.

Should be connected blue port to blue port. I.e., the single port on the Arris to the WAN port on the TP-Link.

Get one device connected and working on the network. See what IP address is assigned to that device.

Then bring on other devices one by one and check each assigned IP address. Or see if one device or another has a problem obtaining an IP address.

 

[WolfTeeth]

Unclone the laptop as the first step. May being looked at as a router (which it is not) and causing network confusion.

Try another known working ethernet Cat 5e cable between the Arris and the TP-Link router.

Should be connected blue port to blue port. I.e., the single port on the Arris to the WAN port on the TP-Link.

Get one device connected and working on the network. See what IP address is assigned to that device.

Then bring on other devices one by one and check each assigned IP address. Or see if one device or another has a problem obtaining an IP address.

Thank you for your reply,

MAC address is uncloned. I have previously tried 3 other ethernet cords that still provided me with the issue.

All devices are able to obtain an IP address until the failure happens (in which case no device is able to). Singling the devices out, when the only device hooked to the router is the PC, the communication between modem and router eventually fails.

 

[Ralston18]

All works well with wireless then. But once the wired PC is connected then failures - correct?

If I have identified your router correctly here is a link to the User Guide:

http://static.tp-link.com/resources/document/Archer_C5_V2_UG.pdf

Look at the LED functions as presented on pages 4 and 5. Determine what the LEDs are indicating versus what you expect to see.

Enable if necessary and then check the router's logs (page 117). See if the router is capturing any errors.

What ethernet adapter is installed on the PC?