Youre not alone - it doesnt work

It is frustrating. I’m planning to buy the Sonos Boost later in the day, I wonder if that would solve it. 

I finally was able to set the surround up with success. With a little bit more research, people or households with mesh network (more than one access points) have a more difficult time setting up the said speakers set up because of network communication issues and it’s configuration. With that said, I know it is a bit extra to be buying Sonos Boost, but it is what solved my issue with setting up the Two Arc+ Two One SLs surround. You would know you are on the right track to success because upon reading the reviews of Sonos Boost, people who bough it commonly share the same experience on encountering the surround set up error because of their mesh network set up. Some would also mention a few alternatives in lieu of using Sonos Boost- like hooking up one of the speakers (i.e Arc) through ethernet cable so that Arc could act like a wifi hotspot for remaining speakers. I have not tried that one and am not sure if that is even accurate. But long story short, if you have the same Surround Setup error issue like mine, buy a Sonos Boost and you'll be fine. 

I have a similar setup with all Ubiquiti network equipment.  I’m also experiencing the surround setup errors.  I even received the errors when the Sonos Arc was connected to LAN (via ethernet cable).  However, the surrounds would appear as configured in the S2 app after the error message.  I thought that meant the surrounds were work.  Unfortunately, the rear channel sound is not reaching the surrounds.  I tried Trueplay Tuning and it failed with the message it lost a speaker.  Sonos Arc connected over LAN did not resolve the issue.

I’m having the same issue. 
the Two One SL speakers work great as a stereo pair. But will not accept the set up protocol from the Arc as surround speakers.
 

 So I have $1500 into this surround sound set up and I need to spend another 90$ on a Boost? There is no other way. So frustrating and Sonos is not addressing this? 

I just had the same problem with my Arc and 2 one SL Surround Setup Error. It took me over half a day to get it working. I share what I did because I had it up and running in 15 minutes once I did this.

I already had an Arc attached to my tv and was looking to add a subwoofer and One SL surround. My Wireless network is pretty basic.

Issues I encountered:

• I was able to add my subwoofer, but
• Adding One SL’s for surround caused the error message “Speaker lost”
• They appeared added, even do the connecting process never fully confirmed completed.
• Without the Arc, they worked as a stereo pair.

If you’re not technical like me, this might help you. I wish I had found this somewhere.

No boost needed for me. No confusing DHCP conflicts I needed to be aware of. No factory resets on my modem, which sent me down the rabbit hole of losing my internet connection completely. 

What I did to get it working

1. I had a network extender, and I unplugged it and had no other apps running on my phone.
2. Turned off all Sonos gear.
3. Rebooted my modem
4. Turned on and reset First One SL 
5. Added First One SL to room.
6. Repeated for the second One SL 
7. Set them up to work as stereo (not necessary, but I wanted to make sure they worked together, which they did)
8. Turned on and reset Arc
9. Added surrounds (they need to unpaired if you did step 7)
10. Turned on and reset woofer
11. Added woofer to Arc.
12. Performed my True Play Tuning.
13. I got hooked straight away to how good it sounds.
14. Plugged in my network extender

I hope this helps somebody.

I’m having a similar setup and the same problem with a customer’s setup. Arc + 2x Sonos One SL + Sub. Everything fails to connect to the ARC.

Current setup…

Network:

Cisco 9800-CL WLC

4x Cisco Aironet 3702i

Did some research on reddit and turned off IGMP snoop, still no dice. I can connect speakers via ethernet and it all works. I even set the devices to connect to the same AP but still no dice.

I can connect the Sonos One SL’s in stereo and add the sub to them just fine via wireless. Something is screwy with out the Arc bar connects to the accessory speakers. I’ve ordered a Sonos Boost as per recommendation of another contributor to this thread. I’ll update if that works.