Wired backhaul and modem on same switch not working

[ovq]

Hi everyone, 

We have all cables (fibre access point and wires to several rooms) all coming out in our basement. Since we don't need wifi there, I wanted to connect the modem  as well as the room-wires to an unmanaged switch, and then set up the router and satellietes in various rooms via ethernet backhaul.

The setup is like this: 

• Fibre optical cable -> Fibre modem -> switch A
• Room ethernet cables -> switch A
• Room 1 -> Orbi Router
• Room 2 -> Orbi Satellite 1
• Room 3 -> Orbi Satellite 2

However, this doesn't seem to work reliably:

The Orbi routrer only is getting a connection to the internet as long as nothign else is connected to the switch. As soon as I have satellites connected, the Orbi router doesn't get any conncetion to the internet when behind this switch. If connected directly to the modem, the Orbi router works immediately. 

Right now, the only 2 solutions seem to be:

• manually connect the Orbi router only, let is establish an internet connection, then connect the satellies (this will not survive a power outage and/or router reboot)
• put the router in the basement and buy another satellite, as the coverage is not enough otherwise. = Waste of money.

Could the switch be the bad boy? Would it make sense to try this with another switch? 

Would the following setup be any better? 

• Fibre optical cable -> Fibre modem -> switch A
• Room 1 cable -> switch A
• Room 2,3,4 cable -> switch B
  • --- patching up switch A + B
• Room 1 -> Orbi Router
• Room 2 -> Orbi Satellite 1
• Room 3 -> Orbi Satellite 2

Thanks for chewing through this. 

[RocketSquirrel]

In my experience, placing a switch between the modem & router is guaranteed to fail. Connect the router directly to the modem and it will work better. 

If the Orbi router in the basement won’t work for you due to Wi-Fi loss, maybe put your old router back into service with its radios off, and put the Orbi into Access Point mode. That’s what I did. My Asus AC68U is a much better router than the Orbi, but the Orbi’s Wi-Fi is better than the Asus. So, for me, that’s the best of both worlds.

[budy]

Or… if the switch is a managed one, create two VLANs on it, where one VLAN has the modem and the RBR's router port connected, while the 2nd VLAN connects to one of the RBR's LAN port the RBS' LAN port and the rest of the rooms as well.

The issue is, that there's some heavy multicasting going on and putting the satellite's ethernet ports onto the same LAN as the Orbi's router port seems to cause network loops, which brings down the entire ethernet. Isolating the two via VLANs should work, as long as your managed switch does it's job correctly. It will need to seperate any MAC addresses to slip between these two VLANs, otherwise will be facing the same situation as before.

[FURRYe38]

Theres known issues with manages switches. Something in IGMP protocols. If one were to have a managed switch, if they can disable this protocol on the switch it should work then. Non managed switches should not present a problem. I agree, the switch should be after the Orbi router and the Orbi router right after the ISP modm/ONT box. 

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@budy wrote:

Or… if the switch is a managed one, create two VLANs on it, where one VLAN has the modem and the RBR's router port connected, while the 2nd VLAN connects to one of the RBR's LAN port the RBS' LAN port and the rest of the rooms as well.

The issue is, that there's some heavy multicasting going on and putting the satellite's ethernet ports onto the same LAN as the Orbi's router port seems to cause network loops, which brings down the entire ethernet. Isolating the two via VLANs should work, as long as your managed switch does it's job correctly. It will need to seperate any MAC addresses to slip between these two VLANs, otherwise will be facing the same situation as before.

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