Ethernet Connection Not Working

[Carbo]

Decided to finally ditch Comcast, or at least my old landline phone and TV. Now, internet only, Extreme Pro tier 400 Mbps.
Purchased a new modem, Netgear CM1100; and a new router, Netgear RAX40. I'm not gifted technology-wise, and that's an understatement particularly relating to networking. That said, it's been a helluva challenge getting this new network up and running. Been on the phone with Comcast and Netgear support. Almost there. . .
I assume this is correct: cable running from the modem to the router and wifi works fine. My laptop sits next to the router and I prefer to be wired into it. But if I run a cable from the router to the laptop, after about 30 seconds or so the wifi connection drops and the ethernet connection says "no internet".
When I unplug the router-laptop connection, wifi comes back. What am I doing wrong?

 

[SamirD]

I'd disable/disconnect the wireless on the laptop. A lot of times laptops don't change network connections properly so the browser will report 'no internet'.

Aside from that, sounds like you wired it all up correctly.

 

[Carbo]

Tried that a few times; just tried it again; same results.

 

[SamirD]

Weird. Is the laptop IP address in the 192.x.x.x, 172.x.x.x, or 10.x.x.x range or something else?

 

[mxnerd]

Open Control Panel, Network and Sharing Center, check IP info for both ethernet and wifi adapters. When you connect the wire, what info changes for wifi connection?

Your CM1100 modem got 2 ports. You should only have one cable from RAX40's WAN port to one of the ports on CM1100, however. and your laptop was connected to one of the LAN ports of RAX40.

 

[SamirD]

Or just run 'ipconfig /all' from the command line and copy and paste the results here.

 

[Carbo]

Weird. Is the laptop IP address in the 192.x.x.x, 172.x.x.x, or 10.x.x.x range or something else?

192.

 

[Carbo]

Wireless LAN adapter Local Area Connection* 14:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Microsoft Wi-Fi Direct Virtual Adapter #5
Physical Address. . . . . . . . . : AE-B6-D0-D2-7A-B9
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes

Wireless LAN adapter Wi-Fi:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Killer Wireless-n/a/ac 1535 Wireless Network Adapter
Physical Address. . . . . . . . . : 9C-B6-D0-D2-7A-B9
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::bd50:b45b:7df3:d1dc%19(Preferred)
IPv4 Address. . . . . . . . . . . : 192.168.1.122(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : Wednesday, July 3, 2019 11:31:36 AM
Lease Expires . . . . . . . . . . : Thursday, July 4, 2019 11:31:36 AM
Default Gateway . . . . . . . . . : 192.168.1.1
DHCP Server . . . . . . . . . . . : 192.168.1.1
DHCPv6 IAID . . . . . . . . . . . : 329037520
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-22-7A-BF-2C-00-E1-12-00-0C-4F
DNS Servers . . . . . . . . . . . : 192.168.1.1
NetBIOS over Tcpip. . . . . . . . : Enabled

 

[Carbo]

Open Control Panel, Network and Sharing Center, check IP info for both ethernet and wifi adapters. When you connect the wire, what info changes for wifi connection?

Your CM1100 modem got 2 ports. You should only have one cable from RAX40's WAN port to one of the ports on CM1100, however. and your laptop was connected to one of the LAN ports of RAX40.

Yes. I have a cable running from one of the ports on the modem to one of the ethernet ports on the router. Left like that the wifi is fine. But if I run a second cable from another ethernet port into the laptop, wifi shuts down and the ethernet connection doesn't work. However, if I run the cable from the modem direct to the laptop, ethernet works. Of course, then I have no wifi.

 

[mxnerd]

Your laptop are not supposed to connect directly to the modem . You will be under attack from the internet all the time. That dual ports are for link aggregation (doubling the speed/bandwidth) if your internet is over 1 Gbps and if your router also supports WAN link aggregation. Use a tape to cover one of the port so you won't use it.

And connect one of the ports on modem to WAN (yellow) port of the router, not ethernet LAN port.

Connect everything behind RAX40 using the LAN ports.

 

[Carbo]

I understand the laptop shouldn't be connected directly to the modem, and it isn't. I tried that temporarily to test the modem. As I said above, the connection is modem to the internet port on the router. That gives me solid wifi. The problem is when I then connect a cable from one of the router's ethernet ports to the laptop. The wifi disconnects and the wired ethernet connection doesn't connect.

 

[mxnerd]

Like I said, have you opened Network and Sharing Center, check IP info for both ethernet and wifi adapters, before and after the wired connection? (or use INCOFIG command line), and did you try different ethernet LAN port? Did you try different cable?

 

[SamirD]

Seems like you've set up the router correctly.

So here's what I'd like you to try next--try hardwiring to another system if you can.

If you don't have another system, download a linux live cd and boot the live cd on the laptop and connect hardwired and see if that works.

 

[Carbo]

Like I said, have you opened Network and Sharing Center, check IP info for both ethernet and wifi adapters, before and after the wired connection? (or use INCOFIG command line), and did you try different ethernet LAN port? Did you try different cable?

Wifi IPv4: 192.168.1.122
Ethernet IPv4: 73.139.63.145

And, yeah, tried another cable and all 4 ethernet ports on back of router.

 

[Carbo]

Seems like you've set up the router correctly.

So here's what I'd like you to try next--try hardwiring to another system if you can.

If you don't have another system, download a linux live cd and boot the live cd on the laptop and connect hardwired and see if that works.

Another system? Do you mean another laptop?

 

[mxnerd]

Wifi IPv4: 192.168.1.122
Ethernet IPv4: 73.139.63.145

And, yeah, tried another cable and all 4 ethernet ports on back of router.

That means your laptop ethernet port was getting an WAN IP and retained it, which is not right.

Again the connection should be like this:
one of the CM1100 ethernet port ---- yellow port of the router

and one of the ethernet (LAN) ports to your laptop's ethernet port.

==
diconnect laptop's ethernet port, reboot, then reconnect. You will then get an IPv4 address in the 192.168.1.x range.

 

[Carbo]

That mean your laptop ethernet port was getting WAN IP and retained it, which is not right.

Again the connection should be like this:
one of the CM1100 ethernet port ---- yellow port of the router

and one of the ethernet (LAN) ports to your laptop's ethernet port.

==
diconnect laptop's ethernet port, reboot, then reconnect. You will then get another IPv4 address in 192.168.1.x range.

 

[Carbo]

diconnect laptop's ethernet port, reboot, then reconnect. You will then get another IPv4 address in 192.168.1.x range.

Did that. Ethernet IP is showing 192.168.1.2

 

[mxnerd]

So does it work now?

You should be able to connect wired and wirelessly to the router at the same time.

 

[Carbo]

So does it work now?

You should be able to connect wired and wirelessly to the router at the same time.

Unfortunately, no. As soon as I plug the cable into one of the router's ethernet ports and my laptop, wifi shuts down and ethernet doesn't connect. As soon as I unplug the cable, wifi pops right back up.
I'm beginning think I may need a hammer to solve this issue.

 

[mxnerd]

This is weird, unless there is an IP conflict between wired and wireless adapters. Try shut down everything and then turn back on one by one.

Sequence is modem, router then your laptop.

==

But the reality is computer will only use one of the connections in any moment,, maybe you can just ignore the issue. Just use one of the connections and forget the other, it really doesn't matter. OS will not combine the bandwidth even if both function simultaneously.

==
By the way, see if there is new firmware.

 

[Carbo]

Running the latest firmware. And the reboot sequence you described has been done numerous times. Ignore the issue? Can't do that. I paid for certain features and technology and expect to receive it. If not, back it goes. I may try one more call to Netgear support. . .but, god, they are dreadful.

 

[mxnerd]

Yeah, return it if it doesn't work.

 

[VirtualLarry]

Ehh, I suspect some non-obvious behavior afoot here.

Most router, use a single ethernet switch chip, with software VLAN control, to segregate the WAN from the four LAN ports.

Unfortunately, due to power/config/overload/hack/glitch/whatever, it's possible for the switch module to "fail open", and then WAN and LAN are commingled together on one switch, with no VLAN separation, no separate WAN and LAN ports. Just switchports.

That is what I believe may be happening here, and his LAN device, plugged into the router, is pulling a public WAN IP, because the router itself (software control system) SHUTS DOWN, and that's also why his Wifi dies.

Whether this is due to some sort of electrical issue (ground loop?), or otherwise, I cannot say.

But it may well be grounds for an RMA, and possibly replace your UPS or power strip as well, it could be at fault here.

Edit: This may also be indicative of some other electrical fault somewhere in the system: Your AC power / power strip / UPS, your cable line's entrance grounding block, your laptop's battery / charger / motherboard, or the router or power brick.

I think getting this properly resolved, would be a bit elucidating, if you have power gremlins afoot. Don't want any dangerous situations. This Cable Modem / Router / Laptop issue could be a "canary".

 

[Carbo]

For what it's worth, I've already contacted Amazon to set up a return. If Netgear, two phone calls and 4 hours later, can't get a handle on this, that's good enough for me. I've got about 10 days to try another router before this one needs to be returned.