CAX 80 & Xfinity Issues

So this has been my setup for the last 6 years:

C7000-100NAS Cable Modem / Router / WiFi but WiFi radio turned off

Wired Ethernet Connections:

1 - R7000 WiFi only (no router) installed on 3rd floor upstairs

2 - EX8000 2nd Wifi name installed downstairs on 1st floor

3 - TP-Link (TL-SG2008) managed switch 1st floor at TV

4 - TP-Link (TL-SG2216) managed switch 2nd floor at TV

TP-Link (TL-SG2008)

1 - To Router

2 - TV

3 - Apple TV

4 - Sonos Sound-Bar

TP-Link (TL-SG2216)

1- To Router

2- TV

3- Xbox

4- Sonos Connect

5- Sonos Amp

6- Sonos Amp

7- Synology NAS

8- iMac

9- iMac

10- Printer

This is what I tested this afternoon:

The laptop is so new it doesn’t have an ethernet port so tests using one of the iMacs downstairs

In the next 2 tests the iMac is the only thing connected to the routers

C7000 —Wired—> iMac

783.4, 759.8, 771.7 Mbps

CAX80 Factory Reset 192.168.1.1 Gateway address

CAX80 —Wired—> iMac

917.4, 920.2, 926.0 Mbps

In the Wi-Fi connection tests below when I am using the CAX80 Wi-Fi because it has a new to my network name and password, only the devices being tested are connected and the EX8000 is unplugged. When I am using the EX8000, the radio on the C7000 or CAX80 is turned off, but since this is my regular network, many other devices are connected, but not really providing traffic. Neither router has any other ethernet connections during the tests, only the EX8000 if being used.

My standard setup

C7000-100NAS —Wired—> EX8000 —Wi-Fi—> iMac about 2ft distance

The Wi-Fi radio on the C7000 is turned off and the EX8000 uses smart connect

585.3, 584.3, 573.5 Mbps

Change Modem Router

CAX80 —Wi-Fi—> iMac about 2ft distance

29.1, 84.9, 75.5 Mbps

Let’s change to smart connect as that is really bad

Enable smart connect on CAX80

iMac 3 ft

799.9, 827.8, 721.1 Mbps

Same as above

iPhone 13 Pro Max about 15 ft distance

430.9, 438.6, 398.3 Mbps

It all looks good to this point

Turn off Wi-Fi Radio on CAX80

Connect EX8000 - the only thing connected

iMac about 15 ft distance

605.3, 680.9, 693.7

iPhone 13 Pro Max about 15 ft distance

578.3, 577.4, 573.6

So maybe the EX8000 has better Wi-Fi

Reboot CAX80 with Wi-Fi off EX8000 connected

All came back ok

Unplug EX8000

CAX80 turn Wi-Fi radio back on and reboot with only cable connection

iPhone connected ok

iMac didn’t connect even with manual DHCP renew attempts

Reboot iMac now have an address and connection

Now make Ethernet connections

Connect downstairs TP-Link (TL-SG2008) 8 port switch

Seems ok

Reboot CAX80

iMac took several minutes to re-establish connection

Otherwise seems ok

Connect TP-Link (TL-SG2216) 16-port switch

iPhone and iMac Wi-Fi connected still ok

This killed the connection to the 8-port switch

Spotify running on Apple TV to Sonos no connection

And 2nd iMac upstairs on 16-port will not connect to the internet even after rebooting the iMac

Reboot CAX80

Downstairs iMac didn’t reconnect even with manual refresh DHCP

Reboot iMac no luck

Reboot iMac finally back after some initial flaky connections

Spotify Sonos not connected through Apple TV

Upstairs iMac has an IP address and can be refreshed, but never connects to the internet

Connect old C7000 to cable, connect 16-port switch, 8-port switch, EX8000, and direct connect iMac so all 4 Ethernet ports occupied, turn it on.

Downstairs iMac direct wired is getting

772.0, 780.3, 766.4

Downstairs iMac through Wi-Fi to EX8000

551.0, 562.6, 579.3

Apple TV Spotify Sonos is working

iPhone 13 Pro Max

484.7, 502.0, 506.0

Upstairs iMac through 16-port switch

768.6, 752.6, 763.5

Both iMacs back upstairs direct connected to 16-port switch and simultaneous tests

iMac 1: 496.8, 374.2, 486.3

iMac 2: 327.1, 421.2, 272.5

At this point I think the CAX80 has hardware issues. It seems to be ok until you load it up, and then it craters. It's possible it doesn't like my switches, but these have been working fine for 6 years and are still working fine connected to the C7000.