Installing OpenWrt through a splitter

I have 4 routers that I need to keep up to date.

Are there any technical reasons why the following could cause problems when flashing Openwrt firmware for updates:

-connect ethernet cables from each router to a splitter ---> connect ethernet cable from splitter to Lenovo ThinkPad Docking Station --> connect Lenovo Dock to computer using USB-C

-when updating/installing Openwrt, I would connect USB-C cable to computer and login to LuCI on router I want to update and then flash new firmware.

Do I HAVE to be directly connected to the router via ethernet when flashing firmware or else something could get messed up? Will routing the connection through a splitter & dock cause any problems for the flashing process?

What is the function of each of these routers? Are they operating as dumb APs? or performing normal routing? or something else?

What is the "splitter" you're talking about here? Is it an ethernet switch? Please define this more specifically (ideally with the brand+model of the device).

I'm not aware of any OpenWrt routers that have a USB-C connection for connecting to a host computer, but if you're talking about a USB-to-ethernet adapter (or one built into a USB-C docking hub), yes, this would work.

This depends on what "splitter" and "dock" you are talking about, among other things.

OpenWrt has wifi disabled by default -- sometimes upgrades require a complete reset to defaults, so you will absolutely need ethernet to connect from time to time for certain upgrades. You don't necessarily need to be directly connected for all of the updates you might run, but it is a good plan to always have the physical capability to do so.

Can you draw a diagram of your proposed configuration?

1 Like

What is the function of each of these routers? Are they operating as dumb APs? or performing normal routing? or something else?

performing normal routing and access points. Each router provides separate network.

What is the "splitter" you're talking about here? Is it an ethernet switch? Please define this more specifically (ideally with the brand+model of the device).

see attached drawing of proposed configuration (Linksys model SE3008: 8-port gigabit ethernet switch)

I'm not aware of any OpenWrt routers that have a USB-C connection for connecting to a host computer, but if you're talking about a USB-to-ethernet adapter (or one built into a USB-C docking hub), yes, this would work.

see attached drawing of proposed configuration (the dock provides usb-c connection to computer)

So your "splitter" is actually supposed to be an 8-port unmanaged switch (Linksys SE3008)?

I still don't really get the purpose behind network topology, but just looking at the first three rows (1-Router to SE3008) just cannot work, not with an unmanaged switch, and even with a managed switch this setup would be …$unconvential.

Although I don't really get what you're trying to achieve, a (smart-)managed switch seem to be necessary, although I still see no reason for 2-Router, 3-Router, 4-Router, if you want them to segment the network (and not just be dumb-APs, that would be easier done on 1-Router alone, with the managed switch bringing out the VLANs - there wouldn't be any need for 2-Router, 3-Router, 4-Router that way. …apart from the network loop in your current topology.

But, please, describe your intentions (a lot) closer, as I'm purely guessing what you might want to achieve.

2 Likes

I agree with @slh's entire post. The topology 1) won't work, and 2) is generally unnecessary (can be achieved more easily with one router and VLANs, but requires a managed switch)..

Using an unmanaged switch will cause major problems for your network since it is not designed to handle more than one network/subnet.

What is your actual goal with your network?

Really sorry. I wrote this at 2 in the morning cause I couldn't sleep. My brain was not fully working obviously.

no worries. Honestly, there are lots of people who call a switch a "splitter" because that is what it kind of does from a high level perspective. (but, there used to be passive splitters for analog phone lines... those types of things would not work and thus why we wanted clarification).

The important part here is that your switch is unmanaged which makes it unsuitable for use with multiple networks. You need a managed switch in order to work with multiple networks on the same physical hardware.

I originally purchased two Linksys routers because I needed to segment one network for work. But I couldn't get the wifi working on the Linksys. So I bought 2 netgear routers and found the Linksys ethernet was faster than the netgear but the netgear wifi worked reliably. Then I needed more ports on the back of the router, so I just used the extra routers to get more ports.

I no longer need isolated network (changed jobs) so it would be nice to plug switch into one router and be able to plug all clients into the switch. I tried this with the Linksys switch but it wasn't working. Sounds like I need a managed switch.

Can you recommend a 24 port switch brand/model that is good for achieving what I want to do? (I'd prefer managed switch (per your instruction) in case I ever need to deal with multiple networks in the future).

Really appreciate your attention and help with this. Very kind of you.

…and then there are adapters which 'split' an eight-lead ethernet (or ISDN) cable into two four-lead ones (fast ethernet), this term really is horribly overloaded.

1 Like

You can do this if you want, just a lot of extra hardware for little gain.

So you really only need one router and one network?

A managed switch can work as an unmanaged one, so yes, a managed switch could be useful... but it is only worth spending the extra money on it if you plan to actually (eventually) use the managed features -- in other words, multiple networks/VLANs. Otherwise, just go with an unmanaged one.

there are dozens (possibly hundreds) of options here... if you go with an unmanaged switch, there is little difference, in truth. If you go with a managed option, just stay away from the entry level offerings from most of the vendors (TP-Link and Netgear both make fine products, but the entry level managed switches are terrible)... at 24 ports, I think they're already above entry level, so you can probably select anything.

BTW, I don't see any references to OpenWrt -- do you have OpenWrt on any of your devices?

Openwrt 22.03 is on all routers.

I think what I would like to do is move to 2 routers. I will use Linksys 1900acs to run streaming stuff that doesn't need wifi. I'll use netgear router to run stuff that uses wifi. Would it be possible to buy a managed switch, connect linksys router and netgear router to the switch and then connect a computer to the switch (via ethernet) and be able to update/install openwrt on both routers (thru the switch) without connecting directly to the back of each router when performing maintenance?

Sounds like you'll want to operate the Netgear router in simple dumb AP mode.

It depends on the types of maintenance and upgrades. Often, it can be fine. But if any of the maintenance requires a reset to defaults (which is sometimes necessary, other times just best practice, and the rest of the time optional), you will probably need a direct connection (and in fact, having it connected to the rest of the network could cause issues when it is in the defaulted state).

It is actually possible that, using a managed switch, you could kind of avoid the direct physical connection requirement, but the truth is that this would be significantly more effort that it is worth.

Bottom line is that you should plan to have the ability to directly connect your computer to each of the routers, and that you should be able to disconnect any of the routers from the main network when that is necessary. It can actually be trivially simple to do this if you have a patch panel or even just well labeled cables all terminating in one central location -- just unplug your the connections that go to your computer and the router in question and connect them directly together instead.