What makes you think a LTE router won’t work with Sonos?  There are many people using them and I have done so in the past.  Have you actually tried to make it work?

If you are basing this on its being ‘unsupported’ then you are misunderstanding what ‘unsupported’ means.

My understanding, which could be wrong, is that some “LTE routers” don’t allow for peer to peer communication.  Your computer, phone, TV, etc, can all access the internet, but the device can’t communicate with each other.  It pretty much works like a guest WiFi network.  Obviously, the Sonos speakers need to talk with each other, and your phone or whatever controlling device needs to talk to the Sonos speakers.  It’s not an issue that Sonos can control or fix.

But some LTE routers do function as a normal ‘full’ router and allow device to device communication.  Or you can get a home router to connect your LTE router and just use what the service provider gave you as a moden.

But again, I could be misunderstanding the situation.

To expand on my comments in the light of @melvimbe ‘s post…

“Unsupported” means that Sonos Support won’t guarantee to provide help if it doesn’t work straighforwardly, because there is significant risk that the router won’t meet Sonos’ greater networking requirements, or because the signal may be weak.

However in my experience (which is not extensive) most proper LTE routers do not enforce client isolation.  Given a decent 4G signal, they will work well.  Client isolation is more common when trying to set up Sonos on a 4G mobile hot spot.

@John B and @melvimbe Agree. In theory it makes no sense why a it cant connect to the Router regardless of the source of internet. 

Today I was trying to register my ARC on the Sonos app and I kept hitting a dead end. I tried the recommendations (off on/reset/connect with ethernet cable etc). Via their chat and then by calling the Sonos rep said as soon as he realised that the Router was an LTE one that it was not possible to register the device and hence at the moment I can only use the ARC manually without updates or the feature on the app. I also assume I wont be able to connect the Sub3/Ones. 

It is odd as I managed to do the initial updates. I have one idea of taking the ARC to a friends house and doing the registration/updates via their fibre router. Then reconnect it to my LTE router at home which might be ok as the current roadblock is only with registering the ARC.

One possibility is to connect the LTE network output to another router and use its WiFi for SONOS and your controllers. Travelers and university students often use a travel router in similar situations where the local WiFi restricts access among clients.

Been using my sonos system on 4g initially and 5g currently 

My arc is hardwired to the router and all but my moves and roams are on sonosnet 

I use eero pro 6 mesh as my wifi and have had no issues in over  12 months 

The wifi on my 5g router is disabled and all my sonos speakers have reserved ip's on the eero pro 

Speeds on the 4g were 80-120mb down and 10 up

I am now getting 350 down and 40 up and happy I switched from fixed broadband 

@skullc Not related to the question, but for future readers. As I understand it the Roam and the Move cannot function on Sonosnet but have to be on wifi.

To copy an older post:

”WM:0 means the devices are running on Sonosnet, with at least one wired component.
WM:1 means the device is running in wireless mode direct to your router's wireless network.
WM:2 means the device is connected to the Playbar using 5ghz wireless, ie it's configured as a surround speaker.”

What WM-value are your Roams and Moves?

@skullc Thats good news. So technically it should work once I figure out how get the product registered/linked.

As posted roams and moves are on wireless rest of system is on sonosnet 

So roams are wm:1 moves wm:1 rest are wm:0

For reference my LTE router's are listed below 

Huawei b535 4g+ bought to test before dumping old isp

Huawei cpe pro 2 isp provided router 

Livewire cpe pro 3 bought to replace isp router when contract is up

I paid £16 a month for an unlimited sim on 4g test period 

Now paying £20 a month unlimited data for 5g broadband package 

Soon I will go back to cheaper sim only 

And yes it really is unlimited I use around 2tb a month

My provider is three in the UK 

@Vice .  I am curious about your expression “register my Arc on the app”.  What you actually need to do is add the Arc to your system.  Or possibly set up a new system starting with the Arc.  It may just have been your choice of words, but could you let us know what steps you are actually taking?

@skullc I currently have a TP-LinkTL-MR6400  https://www.tp-link.com/en/home-networking/3g-4g-router/tl-mr6400/. It’s probably over 4 years old. Maybe older models are the problem and it was easier for the Sonos technician to just allocate the problem having an LTE Router.  

Maybe I got the 4g router on amazon for £45 don't know if they are still there but can recommend it

Update 

Holy…… They are 79 now

@John B Sorry I am new to Sonos and not very knowledgable with this type of tech. On the quick start with the ARC I had to install the Sonos App. Create a “new system”. In that System add the Arc. And as per the screenshot below this is where I am at. I cant register the ARC.  

@Vice its been a while since I registered mine what error do you get?

When I setup my system I was still on virgin media cable  is the arc hardwired to the router?

Do you have any adblocking software running?  VPN?

I note that your settings describe ‘living room’ as unregisters.  Is that the the name you are trying to give to your Arc ‘room’?

And just to be sure, the Arc is the first Sonos device you have tried to set up?  There is no pre-existing system?

@skullc Yes I have tried hard wired into the router. Just tried again as below

@Vice you need to read John b post about any vpn you may have etc

Like I posted I have not registered a system on LTE before so not sure if this would work 

@John B 

I dont have any adblocking software or VPN changing service. No extenders. Just this Router.

Regarding the name. As far as I know I have not given a name to anything. I did allocated this system to “Living Room”. That message “Living room not registered” is linked to the ARC not being registered when I click on it. If that makes sense.

Correct - this ARC is the first device I have tried to set up. 

Clutching at straws a bit now…

 But would you be able to change the DNS servers in your router to Google Public DNS?

If you could confirm exact model of router I don't mind taking a look at whether / how this could be done 

This is what I have done 

Primary  8.8.8.8

Secondary  8.8.4.4

Looks good.  But has it made any difference? I'm not optimistic. 

Edit sorry I just noticed lad post was from @skullc  not @Vice 

Yeah me neither probably work around would be to take it to his friends register it then bring it back 

Once over the registration it should work ok

I have added speakers to my system since using 4g/5g with no problem ie: my moves and roams 

Just had a thought is your phone on the same network as the arc?

@skullc Yes phone is using the same wifi/network when connection/setting up the Arc. However the phone’s network provider is a different company from the router’s network provider. 

“But would you be able to change the DNS servers in your router to Google Public DNS?” - I will try this on Monday. I am travelling this weekend and will put the Arc in the car and try to set it up/register it using the Hotels/WIFI. Long shot. 

BTW this is the router model I have at home: TL-MR6400  https://www.tp-link.com/en/home-networking/3g-4g-router/tl-mr6400/