Strange Home Networking disconnection problem

Mallory Woods · Feb 6, 2017

Background: Router Netgear R7500, Two TP-Link 5-Port Gigabit Switches (TL-SG105). Using Moca as well to connect a few Tivos in the house. Two Actiontec Routers that have been converted into Moca Bridges and two older nim 100 motorola Moca to Ethernet bridges.
The internet connection is FiOS.

I live in a townhouse and fishing wires thru the wall is nearly impossible so I have depended on wireless for my upstairs (3rd floor office - The FiOS and the router is in the basement.

I got the idea of running an cable down from the attic on the outside of the house. I purchased some cable that said it was rated for outside. The connection is from the router to a netgear (ProSafe FS108) switch in a closet.

For a while this connection has been solid with a rare odd occurrence in which things just stop working. I suspected the switch I was using was old so I replaced them with the TP-Link(s). I have not rhyme or reason as to why it would stop but I would reboot all of the equipment, router included and things would work again.

I had an outage today and since I had some time I tried to trouble shoot it. I found out there was an older Dynex (DX-ESW8 yeah sorry) switch that I had forgotten to replace (The 2nd TP Link replaced it) and I thought that maybe I had found the root of my problem. However, when everything came back up none of the Moca devices would connect.

After doing a LOT of trouble shooting, I had to remove the original cable that was run on the outside of the house as when that is plugged in (directly to the router or switch) the Moca devices fail.

I also have a desktop downstairs that had the same issue. But, I replaced the Ethernet cable on that and it works fine. I do have a friend coming by tomorrow with testing equipment but I'm open to suggestions. Obviously that cable on the outside will need to be tested.

Has anyone else had any experience in which when you plug in a cable it interferes with other network devices?

Thanks for the feedback.

7 Wired PC's Connected
4 Tivos' Connected
3 TV's Connected
2 PS4's Connected

There is a Wifi on the network that connects to various devices. This appears to be solid without issue unless wireless fails and needs the router to be rebooted (rare)

No NAS but there is an FTP, Plex Server on the network.

All LAN connections listed above are internal connections not dongles or USB network connectors.

UPDATE 02-06-17****

So I was able to get a friend over with some networking equipment and.. All the lines pass. So I can cross off a bad network cable from the list. I was also able put things back the way they originally were and I have connectivity and moca on the same network. My preference is to get everything on Ethernet if possible and remove the moca devices.

One other thing of note which is weird. I have a connection in the mid level of the house (and this cable tested fine too) that should just plug into a netgear 5 port Gigbit switch (GS605NA) and when I plug this cable into that switch (and remove the nim 100) all PC's on that switch register a connection but can't get out to the internet. I let it sit for about 2 mins and maybe I can let it sit longer if need be. I'm trying to figure out how this works fine over Moca but when given an Ethernet cable it does nothing.

Any responses help. If I diagram is needed I can whip up one really quick.

Thanks again.

Solandri · Feb 6, 2017

Mallory Woods :

This is a long shot, but really old Gigabit and Fast Ethernet hardware (like 10+ years old) had a 2 repeater limit. You could attach a switch to a router (which has a built-in switch). But if you went router w/ switch - switch - switch, devices plugged into the last switch might not be able to see the router because it was going through 3 repeaters.

I ran into this problem a few times a decade ago. Symptoms were really weird - one laptop plugged into the cable would work fine and had Internet access, while another laptop plugged into the exact same cable couldn't even get an IP address. But I haven't encountered it in close to 10 years.

I live in a townhouse and fishing wires thru the wall is nearly impossible so I have depended on wireless for my upstairs (3rd floor office - The FiOS and the router is in the basement.

I got the idea of running an cable down from the attic on the outside of the house. I purchased some cable that said it was rated for outside. The connection is from the router to a netgear (ProSafe FS108) switch in a closet.

Running cable outside the house usually violates HOA standards. Have you tried running cable through the heating/AC vents? Sometimes those offer an easy shot from one room to another. (They're what spawned the meme of tying a string to your cat and sending it through the vent, then tying your network cable to the string to pull it through. Not that I advocate doing this with your cat.)

One other thing of note which is weird. I have a connection in the mid level of the house (and this cable tested fine too) that should just plug into a netgear 5 port Gigbit switch (GS605NA) and when I plug this cable into that switch (and remove the nim 100) all PC's on that switch register a connection but can't get out to the internet.

That sounds more like you have a second DHCP server somewhere on your network. Maybe someone has secretly tried to add a WiFi hotspot by plugging in a router?

The second DHCP server will respond to DHCP requests as if it were your main router. But since it doesn't have Internet, devices which get their IP address from the second DHCP server will have network connectivity, but no Internet. Worse, if the second DHCP server is on a router and its IP address conflicts with your main router's, you'll get mysterious problems where sometimes devices can access the Internet and sometimes they can't.

Each subnet must have only one DHCP server. If you plug another router or add some sort of server computer that has a DHCP server, you must disable the DHCP server on those devices.

Another possibility is that your townhouse's cable TV wires aren't exclusive to your house. And one of your neighbors has MoCA adapters and both your networks are randomly intermingling.

Mallory Woods · Feb 7, 2017

Thanks for the information. I did order some new gig switches (stayed in the TP-Link Family) and as of now everything is working as it should! I'm going to let things run for about a week of normal traffic before I declare this fixed. I have to add one more drop then I can remove all of the Moca devices from the network. Thanks again for your help about the older switches.

Solandri :

Mallory Woods :

This is a long shot, but really old Gigabit and Fast Ethernet hardware (like 10+ years old) had a 2 repeater limit. You could attach a switch to a router (which has a built-in switch). But if you went router w/ switch - switch - switch, devices plugged into the last switch might not be able to see the router because it was going through 3 repeaters.

I ran into this problem a few times a decade ago. Symptoms were really weird - one laptop plugged into the cable would work fine and had Internet access, while another laptop plugged into the exact same cable couldn't even get an IP address. But I haven't encountered it in close to 10 years.

I live in a townhouse and fishing wires thru the wall is nearly impossible so I have depended on wireless for my upstairs (3rd floor office - The FiOS and the router is in the basement.

I got the idea of running an cable down from the attic on the outside of the house. I purchased some cable that said it was rated for outside. The connection is from the router to a netgear (ProSafe FS108) switch in a closet.

Running cable outside the house usually violates HOA standards. Have you tried running cable through the heating/AC vents? Sometimes those offer an easy shot from one room to another. (They're what spawned the meme of tying a string to your cat and sending it through the vent, then tying your network cable to the string to pull it through. Not that I advocate doing this with your cat.)

One other thing of note which is weird. I have a connection in the mid level of the house (and this cable tested fine too) that should just plug into a netgear 5 port Gigbit switch (GS605NA) and when I plug this cable into that switch (and remove the nim 100) all PC's on that switch register a connection but can't get out to the internet.

That sounds more like you have a second DHCP server somewhere on your network. Maybe someone has secretly tried to add a WiFi hotspot by plugging in a router?

The second DHCP server will respond to DHCP requests as if it were your main router. But since it doesn't have Internet, devices which get their IP address from the second DHCP server will have network connectivity, but no Internet. Worse, if the second DHCP server is on a router and its IP address conflicts with your main router's, you'll get mysterious problems where sometimes devices can access the Internet and sometimes they can't.

Each subnet must have only one DHCP server. If you plug another router or add some sort of server computer that has a DHCP server, you must disable the DHCP server on those devices.

Another possibility is that your townhouse's cable TV wires aren't exclusive to your house. And one of your neighbors has MoCA adapters and both your networks are randomly intermingling.

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Strange Home Networking disconnection problem

Mallory Woods

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Solandri

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Mallory Woods

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