Exact same issue here. According to this post 

my Connect’s manufacturing date is August 2015. I’m trying to downgrade to S1 without succes. In the middle of the process my Connect doesn’t seem to be able to connect to my home network, neither by wifi nor by ethernet cable. In the ethernet connected case, I see a steady green LED and a blinking yellow LED on the ethernet port.

What did Sonos support say about it, when you called in?

I am having this exact issue as well. I had this connect in storage for over a year. Pull it out, plug it in, orange and white flashing, never goes green. I see it on the network, but can’t connect to it. Factory reset does nothing. Nothing about the network or set up has changed. It was just in storage. 

More likely caused by the Illuminati. 

This is suspicious, could Sonos have deliberately sabotaged the Sonos Connect, or made a mistake in the software update? I also have the same problem here.

I have had contact with Sonos Support and conclusion was: device is dead, that’s what orange-white flashing light after factory reset means.

Have you tried to call Sonos Support directly to discuss it?

Same issue. Sonos Connect working fine. Gone for 3ish weeks, when I come back app can not detect and can not factory reset. Nothing here ?

I have exactly the same issue, was any fix found?

Thank you for your help,

The Connect is connected to the LAN and the port lights are flashing as per normal.

Still no reset ….

As a test, wire the CONNECT to the LAN.

In general, Factory Reset complicates issues.

When you wire to the LAN, lack of or erratic port lights indicates hardware failure.

Thank you for you fast reply!

After running successfully for two years, the Connect was powered down for 3 weeks while I was away. 

When I returned the Connect powered up only to the stage of having a flashing white LED.    The Sonos app could not see the Connect to bring it into the Sonos system.

I tried a factory reset that did not result in a flashing orange-white but never a permanent green LED.

Interestingly, the Connect often transmitted an SSID for a connection, and the Sonos app did sometimes see the Connect, to connect to it, but the remainder of that installation frose at that point (the Sonos app did not progress with the installation).

So I tried more factory resets that failed (flaashing white-orange but no green led)

I think the Connect might have a corrupted OS-Software. 

 - Is there a way to write the a base load software directly to the Connect?
 - is there a way to debug a Connect that does not factory reset?

I feel like the hardware is OK, but the software might be corrupted.   I don’t want to be forced into buying a new box for this simple prioblem.

Thanks in advance for any help.

Hi.  Failure to factory reset normally indicates a hardware failure.  What is the back story here?  Why are you trying to reset the device?