Trouble with TP Link Archer C5400 and Motorola MB8600 - Router drops connection repeatedly since upgrading modem

[npapcun]

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Router Make and Model - TP Link Archer C5400
Modem Make and Model - Motorola MB8600

Setup is currently the modem hardwired directly to my Media Center Tower. There doesn't seem to be any issue with the media center connection, but my motherboard is:
ASUS M5A99FX PRO R2.0 - onboard gigabit ethernet
Win 10, fully updated.

All cables are Cat7.
No switches
No NAS

All drivers on PC/Modem/Router have been updated to most recent version.

ISP - Comcast, newly upgraded to 1gb Download speed, was on the 250Mbps plan. See below for more details.
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Hello Forum, I hope someone can assist:

We recently ended our promotional rate with Comcast and while negotiating a new rate I was happy to see they had started offering 1000Mbps down service in my neighborhood. Bought the new cable modem to make sure I had DOCSIS 3.1 standard. I've had the TP-Link C5400 Router working flawlessly with a Netgear CM500 since November, 2017 when I purchased both.

I activated the modem through Comcast with little trouble. Called TP Link support and they helped through some basic settings. About 2 hours later, my connection broke. Called twice more and finally it seemed to be ok after a "supervisor" had me switch off NAT Boost and switch from dynamic to static IP. This worked for about 24 hours, then it broke again.

I've had multiple calls, esculations and am currently watiing since last Thursday for the US RMA department to contact me in regards to helping me exchange the router for the DEco system they offer, since TPLinks support feels this is easier than actually fixing the router. Since the response has been so low and sporadic, I'm not expecting any contact before 3pm today when I'll be hitting the 48 hour SLA the last rep told me was standard for the RMA department.

In addition, the modem has been half dropping connection. I can get to webpages, but Slack App will not connect automatically (the "trying to connect to slack" animation plays for a bit or I turn on and find the big X "Unable to Connect" picture) and trying to connect to Blizzard's gaming service takes a long time to get logged in and then it time's out when trying to connect an actual game. When I called Comcast about this, I was told to unplug the modem (not just turn off) and then disconnect the coax from the wall for 2 minutes before turning back to reset the MAC. I'm very close to sending this back and just exchanging for a NetGeat Nighthawk.

Does anyone have any knowledge of this combination?

Sidenote: TPLink's support is terrible.

 

[Ralston18]

This connection?

ISP (Comcast) ---- coax----> modem ----- Ethernet----->Media Center Tower

Where is the router connected?

What other network devices do you have and where (and how) are those devices connected?

 

[npapcun]

Currently I have that connection. I'm hoping to have it be ISP (Comcast) ---- coax----> modem ----- Ethernet ----- router ----->Media Center Tower. As of 2 days ago when I got a connection through the modem I have not tried to re-connect through the router.

Just so we all understand how it's been happening, when I've gotten reconnected by speaking to tplink's service, it will come up and be blue lights across the board. Then, variable from 1-24 hours (most of the time t was 1-2 hours) before, seemingly with no reason, the blue light for internet connection being "good" goes to orange/red which is LED indicating "lost connection". Rebooting the router and modem works about half the time and I have given up using the router.

TPLink's solution is to send me a new mesh router system (Deco M5) instead of correctly configuring the C5400. This is not my preferred solution, and while I'm still waiting for the RMA department to contact me, I'm seeing if somebody can help me get this configuration working.

 

[Ralston18]

Seems intermittent.

Do you have any other known working Ethernet cables available? Try them.

Make sure that the modem and router have solid electrical connections as well. Both at the wall plug and at the respective device.

 

[npapcun]

All electrical is solid. Standard wall plugs and fully seated in the respectable units.

I've had two lengths of cat 7 running from the tower and the modem (router when it was connected). One was a brand new cable I purchased a couple weeks back. The other was the cable I had bought back in November to go with the new router. Results the same on both.

 

[npapcun]

Again, I was using a different (slower) cable modem and the same router since November, 2017 and the original cable I mentioned above, with no issues. I hooked it up, activated the modem and didn't even lose a connection enough times in those 7-8 months to remember it as anything but always on internet.

The only change was the new modem and then a new cable as I was troubleshooting, as well as upping my speed with my ISP.

 

[Ralston18]

Three immediate variables:

new modem, new cable, upped speed with ISP.

"Brand new" no longer means that a product is functional as intended. Overall, I tend to trust, but verify, older products as being what they should be. New cables - sure at face value. Truly working - not so sure.....

The key for you is to methodically eliminate possibilities.

Try the cables in other known working situations. Swap in another modem if you can.

Verify that every component works as it should in some other environment.

That said, let TP-Link send you a replacement. Perhaps they know something we do not. And they will not tell us what "that" is.