Ethernet switch disconnects devices directly connected to G1100

[mcar91]

Something is fishy with my network. I've recently added a 5-port unmanaged ethernet switch (TP-Link TL-SG105) to my network. When the switch is connected to my G1100 router, the ethernet devices attached directly to the G1100's ports cannot be reached.

Disconnecting the TL-SG105 from the G1100 solves the problem immediately. 

The network has worked for a few hours at a time without issue but eventually the G1100's "local" devices end up unresponsive. 

I realize this is a bit of an odd one, so I made a diagram to help: 

Some things I've already tried:

• Different cables between the G1100 and TL-SG105 don't change the result.
• I used a cable tester on the cable connecting the G1100 and TL-SG105 and all is good.
• Got a replacement TL-SG105 and the behavior is the same. Makes me think it's the router.
• None of the devices on my network are running their own DHCP server.
• I've reached out to TP-Link's support and have not yet heard back but since it's an unmanaged switch, I think it's pretty benign. 
• Wifi is entirely unaffected by this issue and continues to function even when the G1100's ethernet devices are not working.

My gut says it's something funny in the G1100's configuration. 

Does anyone have any thoughts? 

[Edg1]

There isn’t really any configuration for an un-managed switch. Can you account for all your patch cables? For example do you have one patch cable plugged from one lan port to another lan port? That is one thing that will cause the issues you posted about. 

[mcar91]

What do you mean by “from one lan port to another lan port”? 

I can confirm no cables are plugged into the same device on both ends. 🙂

[Cang_Household]

Edg1, I concur with your opinion.

Seems like the 4-port ethernet switch chip on the G1100 is having issues with the TP-Link. I believe that TP-Link is IGMP snooping-capable, are you running any Multicast traffic (FiOS TV One Mini uses IGMP too)?

I have a TL-SG108, the 8-port counterpart of your switch. I might need to experiment it myself with G1100, but I need to rip my network infrastructure apart 😓.

Edg1, does G1100 support STP? I see FiOS Network Adapter supports STP surprisingly.

[Cang_Household]

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@mcar91 wrote:

What do you mean by “from one lan port to another lan port”? 

I can confirm no cables are plugged into the same device on both ends. 🙂

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That means looping connection, assuming no Link Aggregation (both G1100 and TL-SG105 are not capable).

Then, do you have Multicast traffic? Can you change a switch to see what would happen?

[mcar91]

I don't believe I have any multicast traffic on the network. I don't have any other Verizon products (no TV, no DVR, no phone, etc.). 

I have two of the TL-SG105s — only one is connected. I've swapped them out and both have exhibited the same behavior. 

Things seem to work fine for a couple hours at a time and then the only way to restore connectivity to the devices connected to the G1100 directly is to disconnect the switch. When I reconnect the switch, it typically doesn't work. I need to wait a few hours before reconnecting. 

The time element makes me think it's DHCP related but I'm not sure. Wireless devices included, there are only about 30 devices on the network. 

[mcar91]

@mcar91 wrote:

What do you mean by “from one lan port to another lan port”? 

I can confirm no cables are plugged into the same device on both ends. 🙂

That means looping connection, assuming no Link Aggregation (both G1100 and TL-SG105 are not capable).

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Re: network loops, I did some Googling and found this support article over at NETGEAR.

One of the devices on my network (connected via ethernet to the TLSG105) is a MacBook which is connected with both wifi and ethernet. Most of the time, I have the wifi turned off, but sometimes I forget to turn it off. 

I currently have the MacBook connected to both wifi and ethernet (via the switch) and everything is working correctly. I wonder if things will break when the DHCP lease goes to be renewed? It currently has 2 IP addresses (one per connection). I'd hate to think this would break everything. 

Last weekend, the ethernet-on-G1100 issue was happening and I don't believe the MacBook was connected to both at any point over the weekend. I could be wrong though. 

[Cang_Household]

I don't think it is DHCP or multiple NICs connect to the same device. What I have here is a Windows with two IP addresses on WiFi and two IP addresses on a RJ45-USB (not possible for IOS devices) adapters for redundancy and simultaneous access to two subnets.

Anything related to IP addresses is considered to be layer 3. Your TL-SG105 and G1100's LAN switch are both layer 2. IP addresses (including DHCP) are kind of irrelevant here. The document from NetGear only shows the scenario of a layer 2 loop. Technically you can have a layer 3 loop too, buy you don't have a layer 3 switch or static routing going on.

Can you maybe swap a brand for the switch? Let's try NetGear unmanaged for a similar price level. I have a Cisco switch that works with G1100. That is expensive and unnecessary though.

[Edg1]

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@Cang_Household wrote:

Edg1, does G1100 support STP? I see FiOS Network Adapter supports STP surprisingly.

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Not 100% sure. I would have to look at the manual. 

[mcar91]

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@Cang_Household wrote:

I don't think it is DHCP or multiple NICs connect to the same device. What I have here is a Windows with two IP addresses on WiFi and two IP addresses on a RJ45-USB (not possible for IOS devices) adapters for redundancy and simultaneous access to two subnets.

Anything related to IP addresses is considered to be layer 3. Your TL-SG105 and G1100's LAN switch are both layer 2. IP addresses (including DHCP) are kind of irrelevant here. The document from NetGear only shows the scenario of a layer 2 loop. Technically you can have a layer 3 loop too, buy you don't have a layer 3 switch or static routing going on.

Can you maybe swap a brand for the switch? Let's try NetGear unmanaged for a similar price level. I have a Cisco switch that works with G1100. That is expensive and unnecessary though.

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I have a few things to report! First, the TP-Link switch worked for 4 or 5 days straight without any interruption. The issue reappeared over the weekend.

I then replaced it with a Netgear switch (GS-305) and the issue appeared after about 8 hours of the the Netgear switch running. Same exact symptoms — all ethernet devices directly connected to the G1100 went offline until the switch was disconnected. 

Any other thoughts? 

I reached out to Verizon's support and they won't do anything except send a tech out to my apartment which feels like a dead end.