No, the Arc connects to the Sub using its own 5 GHz radio, so WiFi must be enabled on the Arc and Sub.

Thank you @GuitarSuperstar for your response. My bad if I was not able to clearly communicate the question. Do Arc and Sub always need a third party Wi-Fi network? Once Sub is powered on, it creates a Wi-Fi hotspot (in simpler terms) to which Arc can connect directly. Is my understanding correct? If yes, ideally - one should be to use Arc (connected to TV) with Sub and play whatever audio comes to Arc from the TV even when there is no wired/wireless network present in the room. 

Sonos requires a network. Why can you not provide one? 

Hi, Sonos requires a 5 GHz radio module. 

Pardon? Sonos doesn’t “require” a 5GHz radio, in that routers/WiFi can be 2.4GHz only. A home theatre master player has its own internal 5GHz access point for its satellites.

​I am just trying to figure a way out to run the Arc+Sub combination as an extension to TV and that’s it. The arc should pick audio signals from the TV via the eARC port, and the sub should compliment the Arc by taking over the low frequencies. Sub should be able to connect to the Arc on its own without taking the route of a third-party network (wired or otherwise).

Thanks @shkoropat 

While I am familiar with 2.4GHz and 5GHz radio, what I am not able to wrap my head around is this.

DOES SONOS ARC need a third-party WiFi (let’s say wireless network controlled by a home router) to connect with SONOS SUB? I understand that in order to stream content from SONOS, or any other services, SONOS speakers need internet, and for internet - they need to connect to the home network - either wired or WiFi. But consider the following scenario.

Arc connected to a TV with an eARC port. Also, Arc is not connected to the home router - neither via WiFi nor ethernet. The TV receives content from a Blu-ray player. In this case, Arc will play the audio without any trouble. Now, if I have to connect the sub to Arc, why can't I just power the sub on, and press the infinity button on Arc as well as a sub to pair them instantly? Wouldn’t it be great from a customer experience perspective? Why there should be a dependency on home routers?

I understand that Arc and Sub both individually may need to be connected to the internet for updating the software etc when you unbox it for the first time. But once you have clubbed them together as a unified system, they should be self-sufficient to exchange signals instead of being dependent on third-party WiFi. This is exactly how it happens in other high-end home theatre systems - be it Bose, Sony, Samsung, or JBL. The sub always pairs on its own with the soundbar for all these brands - irrespective of buying them as a system or individual modules. 

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https://support.sonos.com/s/article/126

Network requirements

General requirements

• High speed wired internet connection such as cable, fiber, or DSL
• WiFi router
• Sonos app and all Sonos products are on the same subnet

To be absolutely clear, if it wasn’t already obvious, Sonos is a networked audio system. It has to have a network, not only for internet software updates but also to manage the IP address space.

If all you want is a simple soundbar, hooked to surrounds and/or sub wirelessly, you should look for a different product.

it was loud and clear the very first time. Just that I was challenging the architecture. I already bought Arc+Sub because of the audio quality. Was just taken aback by the whole setup and getting started experience.

Sorry, but it sounds like a case of caveat emptor then. 

I still don’t understand why you can’t connect to a network. You’d need a network anyway to enable a Sonos controller app to configure the Arc setup on a routine basis.

Sorry if I was not clear earlier. I have a WiFi network connected to the internet and my system is arleady up and running. I was mulling over WHAT-IF kind of scenario. 

If the question is “what if the router dies?” then it’s possible that the Arc+Sub will continue to operate for TV audio only, at least for a while, using their existing IP addresses.

When the IP leases expire the situation could become unpredictable. The units may then operate in AutoIP/APIPA mode, but you’d be in completely unsupported territory.

You can of course try this for yourself by powering off your router.

may be this is the question I should have started with Thanks for that. Tomorrow, I am going to try turning the router off and see what happens. I already tried this with Arc (standalone) and it worked well as far as playing audio from the TV is concerned. Will try with Arc+Sub combination.

The router would typically lease IP addresses for 24 hours. After 12 hours therefore the units would attempt to renew the lease.

You’d probably need to leave the router off for 24+ hours to see what really happens between the Arc and Sub.

Thanks for that tip

@ratty had a little bit of luck. It’s possible to use Arc ‘out-of-box’. Just unbox it, power it on, connect to the TV with eArc and it’s good to go. No need for the S2 app, local network, or internet. TV will control the volume via eArc. of course, connecting Sub will not be possible. Will move this to a separate thread. 

I’m not sure you’re correct, and one could only verify by factory reset (which I’m not about to do).

As far as I can recall Sonos home theatre products won’t play TV input until part way through the app’s setup process.

I did factory reset. Arc and Sub, both. I bought the system three days ago and it's my first Sonos system. So I didn't have anything to lose by factory resetting the whole thing. Arc worked without any set up (for the TV input). Didn't even have to take my phone out. 

In that case I stand corrected.

Of course using the Arc as a dumb standalone soundbar, without internet access or software updates, is not what users do.