The easiest way to prevent similar issues would be to power down any SONOS systems in the office while you build your customer system. Unless you are dealing with MOVE or ROAM, I’d wire a unit to the office LAN. If you have a MOVE or ROAM in the system and you want to fully configure the system at the office, you’ll need an access point in the office with the same credentials as the customer’s system.

If asked, be sure to indicate that you are creating a new system, not adding to an existing system.

Thanks for your advice.
I tried to do what you say, I turn off all the Sonos devices and I simulate the same network as the client (192.168.33.0).
I create a new customer account and pair the devices.

When I go to the customer and install the devices, I log into the customer's tablet (with the new account I created in the office) but the devices are already paired.

I think that Sonos devices also match the router (maybe with a mac address) with which they are configured.

Is this possible?

is it clear what I mean?

Is there a solution for my case?

Thank you so much

You say: “When I go to the customer and install the devices, I log into the customer's tablet (with the new account I created in the office) but the devices are already paired.”

I thought that is what you wanted?

Isn’t this “mission accomplished” -- walk into the customer site and simply turn things ON? I’m not sure what you mean by “paired”.

Since SONOS uses DHCP, the major requirement is that all of the SONOS units are on the same subnet and are members of the same household. And, of course, if you are using WiFi, rather than SonosNet, you’ll need to supply the correct SSID and password. At the customer’s house all you’ll need to do is install controllers on the customer’s devices.

I recommend that you reserve IP addresses at the customer site. This will minimize call backs later, after the customer’s router is rebooted.

Thanks for your answer.
Exactly what I thought, I go to the customer's house, turn on the devices previously configured with the new account in the office and that's it.
I login with the tabliet of client to the same account but the devices are not present (I would have to reset them again).
I suspect that the system is tied to the mac address of the router.
I have recreated the same network as the client in the office, the only different device is obviously the router.
In the office I don't have the client's router but I have recreated the same network (192.168.33.0)

How is the Sonos system connecting to your client's network? Cable or wifi? 

Were any SONOS devices present in the customer’s home before you added these units? The new units would not necessarily be discovered immediately. Rebooting the customer controllers would speed the process.

In your office you don’t need to recreate the customer’s IP address range because the SONOS system will work all of this out as it boots on the customer’s network.

There seems to be some confusion about basic principles. The router’s MAC address is irrelevant. As noted, the office’s IP range is irrelevant as Sonos uses DHCP.

If the client’s system is to work in SonosNet mode that at least one component must be wired to the network. If the tablet-based controller can’t see it then something -- quite possibly the router -- could be blocking communication. Perhaps it’s failing to forward discovery multicasts between the WiFi and wired segments (some awkward routers do this) or, rarely, the router has put the WiFi segment onto an entirely different IP subnet.

If the client’s system is to work in WiFi mode then the system clearly needs to be told the WiFi credentials first. Wire the system temporarily and use the controller’s Settings>System>Network to do this. If, when the system has been returned to WiFi operation, the tablet controller can’t see it then the router could be failing to forward discovery multicasts between WiFi bands (again, some awkward routers do this).

All is connected with cable

Is there a mesh WiFi in the picture? If so where is the Sonos system wired to? 

No, it’s all connected by wire

Including the tablet hosting the controller app?  

Tablet is connected by the wi-fi generated by main router (No VLAN, same network), 192.168.33.0

And the Sonos units are wired back to the router presumably, via switches as necessary.

What router is it? 

Sonos are wired into Cisco Switch.
Pepwave Balance 20 is the router.

I will try soon again, I will be careful to don’t forget nothing
 

Look for any settings which could potentially block multicast traffic. That router has a few. Depending on the switch model you might find some there too. Also, try toggling IGMP Snooping settings.

Make sure that STP, not RSTP is enabled on the switch.