Hi. Does "single Connect"" mean you have no other Connects or that your system consists of a single Connect (or rather  used to consist)? Are you resetting up a system or adding the Connect to a system that already exists?

S1 or S2?

The order in which you may have done things, might ‘possibly’ be your issue here. You mention you reset the Sonos App, reinstalled it and then performed a factory reset of the Connect, which presumably was using a wired ‘SonosNet’ connection, so it might be the case you connected the App back to the ‘existing’ Sonos Household, whereas if it’s your one and only device you will need to create a brand new Sonos HH and not use the existing one.

My thoughts are to try this (assuming it’s your one and only Sonos product) factory reset the Connect and also then reset the mobile Sonos controller App … On opening accept the T&C’s and first create a new Sonos System/HH to which you then add your reset Connect that will have a flashing green statue LED and continue on from there.

Note too that your mobile Sonos controller device must meet the system requirements mentioned here…

https://support.sonos.com/en-us/article/sonos-app-requirements

The WiFi network should ideally be 802.11b/g/n compatible (2.4Ghz band) and use security mode WPA2 Personal.

If problems persist, then perhaps try wiring the Connect to the LAN.

Only do the above though if the previously reset Connect is your one and only Sonos product.

Thank you for the responses.

I hope the following text answer the questions:

My system is a single Sonos Connect Gen 2 running S2-generation software. After wiping everything to start fresh, I no longer have a functional system.

I launched the Sonos app to set up a new system. I followed the instructions and reached the step where the Connect's status LED flashes green. After pressing the button on the Connect as instructed, I received an error message saying it cannot connect.

I am using a Samsung S21 phone with the latest Android version.

The issue is that I cannot install the system either over a cabled LAN or via WiFi. No networks are identified, even after disabling all network security. I also tried manually entering the WiFi name and password, but it still won't connect. Additionally, I cannot find an option in the Sonos app to set up the system via the LAN connection.

It might be best/easier to perhaps speak with Sonos Customer Support direct - I recommend you give them a call. Here is a link to contact the Staff…

https://support.sonos.com/s/contact

I suspect that the Connect software  is just too old for a user to  be able to create a new system. You should call Sonos Support - they can normally force through things that we cannot, and get it set up.

I am using an old UNIFI AP Long Range b/g/n certified for the WIFI.

Yes, You are probably right. I will call the support. 

You implied you have tried doing the setup with the Connect wired?

I ‘think’ you may have to enable ‘multicast discovery’ on your unifi WiFi device too - have you explored that, as mentioned on the manufacturers website? I mention it based on what I just read here at the below link:

https://help.ui.com/hc/en-us/articles/18930473041047-Best-Practices-for-Sonos-Devices

Thanks Ken, you outshine the Sonos support. I only got questions from the support and no real answers.
I allowed the Sonos system (MAC address of Sonos) to send broadcast messages on my WIFI. Now the system is installed and running again.

Sonos design is “fun”. I have not reconfigured anything after the installation. My Sonos system is not connected over my WIFI, it is connected over the LAN, as I want. Great.
Thanks. BR / Marten

I guess there is no WIFI defined on my Sonos system. The Broadcast is over the LAN from my Sonos system to my mobile (which is connected with WIFI). If I unplugg the LAN cable from the Sonos system there is no failover to WIFI. Anyhow, I hope the networking is good enough now, right?

You’re currently using a (wired) SonosNet system - see the difference here between a wired and wireless setup:

https://support.sonos.com/en-us/article/choose-between-a-wireless-and-wired-sonos-setup

If you want to use wireless setup instead, then see this link (second section):

https://support.sonos.com/en-us/article/switch-sonos-between-a-wireless-and-wired-setup

My own preference these days is to use a wireless Sonos system with a Home mesh WiFi, as I have wireless Sonos devices around the home that are capable of using the faster 5Ghz WiFi band - wireless SonosNet uses the slower 2.4Ghz only but it is an ‘exclusive’ wireless signal for Sonos products only - so it’s a case of swings & roundabouts to what some users prefer to use.

Here’s a list of Sonos products that support a 5Ghz WiFi connection:

• Play:1
• Play:3
• Play:5 (Gen 2)
• Sub (Gen 1)
• Sub (Gen 2)
• Era 100
• Era 300
• Move 2
• Roam
• Roam 2
• Roam SL
• Five
• Move
• One (Gen 1)
• One (Gen 2)
• One SL
• Port
• Arc Ultra
• Sub (Gen 3 & 4)
• Sub Mini
• SYMFONISK Bookshelf (Gen 2)
• SYMFONISK Floor lamp
• SYMFONISK Picture frame
• SYMFONISK Table lamp (Gen 2)
• SYMFONISK Bookshelf (Gen 1)

It’s also helpful to have the routers 2.4Ghz WiFi band using a ‘fixed’ non-overlapping channel 1, 6, or 11 and if the router allows, set that bands channel-width to 20Mhz only.

If using SonosNet, with device(s) wired direct to the main router ensure the wired device is set at least one metre away from the router and other wireless equipment …and set its channel (via the Sonos App) to one that is not in use by the local routers 2.4Ghz band.

When running Sonos products on the routers WiFi signal, then also look at the Sonos device SNR levels in thd Sonos App, as mentioned in this Sonos Support link…

https://support.sonos.com/en-us/article/understanding-the-network-details-section-in-the-sonos-app

Ensure your Sonos device SNR levels are set to 45dB, or higher, (if that’s achievable with your WiFi setup). In any event do not have them connected near, or below 25dB… that’s a poor connection.