Router issue

I have two routers in my home. Router A is the one from my ISP. Router B is mine, which the ST hub is connected to. I have the modem from the ISP, which both routers are then connected to.

Long story short, I was looking to ditch router B. But when I hooked the ST hub to Router A, the hub never recognized when I arrived home. But the odd thing is, when it’s connected to router B, and my phone automatically connects to router A, it does recognize my phone as being at home.

Here’s the other odd thing. When I go to the ST settings on my phone (iPhone) the place to select what router to use is greyed out. it shows router B as the router it’s connected to, but I can’t change it.

a couple of things to keep in mind when using multiple routers behind a modem with just one ISP WAN IP address is that only 1 router, usually the one right after the modem, can have DHCP on. DHCP is what hands out the LAN IPs to all your local devices on the main router and any routers plugged into it. then you turn off DHCP on the routers plugged into the main router. if you dont do this the different devices plugged into the different routers wont be able to see and communicate with each other. think of it as a firewall between each router where each router blocks devices not on its own router.

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That make sense up to a point. But, when I moved the ST hub to router A, and my phone was connected to it, it wouldn’t detect I was home. That probably goes back to the other issue that I cannot change what router the hub is connected to in the settings.

First rule of home automation: “the model number matters.“ Even for network routing issues. So we need to know the brand and model number of both routers and of the hub. :sunglasses:

Awestun is correct and brings up great points.

How do you have two routers connected to one modem? Typically an ISP modem has only one Cat5 port that connects to the WAN port of the router. Is the second router is connected to one of the LAN ports of the first router to the WAN port of the second router?

The separate routers are probably handing out addresses with a class c network with 192.168.1.??? So if you look at each devices IP addresses, they appear to be on the same network but they are not and will not communicate with the other router’s devices. You may even see devices with the same address but that’s because they are connected to two separate routers. An example would be you have a laptop and wireless printer. The laptop is connected to your router but the printer is connected to your neighbors router. They will not communicate with each other.

Are they set up LAN to WAN or LAN to LAN? Either is possible with most modern modems, but they have different results as far as sharing.

I am work at the moment, so I’ll check model numbers when I get home, but to answer one of the questions, my ISP modem has four LAN ports, not one. Each router is plugged into it’s own LAN port.

But, those questions aside, does anyone know why the router name is greyed in the settings on the ST app?

the only way i would see workable to have 2 routers directly connected to 1 modem is using a dumb splitter (like the old telephone dumb splitters) for ethernet and then have each router specifically set to connect to a specific IP from the ISP. this isnt something the average end user does.

That’s true, but for residential set ups there are definitely modern modems which will allow you to have either LAN to LAN or LAN to WAN. One router will be the primary. The question then is whether the secondary is just a secondary, essentially in bridge mode, or whether the secondary has its own addresses, so it’s setting up an island network.

Some of the newest gigabit modems assume you’ll be running two routers, like this gigabit Arris model:

But to use that feature as designed you have to be paying for a second IP address.

Alternatively it might be used for port aggregation for super fast speeds, but very few residential ISPs offer that yet.

I have 2 routers as well… the ATT cr@p (BGW210) is set to pass through with everything turned off (WIFI, firewall, etc). The WAN IP is passed to the cascaded router which is a Unifi Dream Machine Pro. Everything on my network connects to the Unifi network. The BGW210 is there just for authentication (there is a way to have the UDMP do it but it is a hassle) and to enable a DVR I haven’t used in 6 years…

@Ghostrider - Where does the ST app show the router name? Why would it even show it? If anything your phone will show the WIFI network SSID you are connected to. If you have WIFI enabled on both routers, make sure your phone connects to the WIFI network served by the router that is also servicing your ST hub. Also, as others have stated, ensure that only one of the two routers is giving out IP addresses. At the very least, change the private addresses that each router uses so it becomes more obvious if something is configured incorrectly. In my case the ATT cr@p is using and the UDMP is using for all my LANs / WLANs / VLANs.

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It turns out I was mistaken on part of this. My apologies. The modem only has one Cat 5 port, which is connected to the ISP router (Router A). Router A has the 4 Cat 5 ports, which router B is connected to. That one is a TP Link AC 1750. But it does have it’s own IP address.

@ aruffell - When you are in the ST app, it shows the name of the router that it’s connected to. But now that I’m typing this, it’s occurred to me that maybe it’s just showing which one. I was thinking you had to specify and enter the router password. When I have a chance, I’ll swap it back over and see if it changes.

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@Ghostrider - Curious to see what mine says. Where does the ST app show this?

Go to the ST app, and hit the three bars in the top left corner of the scree. Then hit the gear on the top right corner, then scroll down.

But, I’m not home, and never thought to look at it other than at home, and now it’s not showing any router. So, maybe that’s showing what router my phone is connected to. But it still says “Change device Wi-Fi network”, which the wording would lead me to believe that it’s asking about the network the hub is connected to, but that may not be the case. I’ll switch my phone between the routers when I get home and see if that changes.

Under the “Change device WIFI network” I see this:

Dog House is the name of the “location” and STHv3 is just the name of my ST hub. I vaguely recall, and brief searches seem to confirm, that you can connect the ST hub to the network via WIFI. If so, then you would be seeing the SSID of your wifi network listed there (which you may have set to match the router name…) anyhow I definitely prefer to hardwire anything I can for added reliability and have therefore never used the ST hub via wifi.

This brings me back to the wifi network(s) you may have at home. Make sure that wifi is off on router A and if you want to keep it on for any reason (I do not recommend this), make sure you do not name the wifi network the same as on router B. Your devices may be hopping from network to network and you would likely not notice when it comes to internet access but access to local devices is likely impacted.