@jujiba 

Reading back through the thread here, it makes me think it’s ‘quite possibly’ the router, as that ‘brand’ is not particularly highly rated online, by all accounts - maybe the time has come to consider simply changing your router?

It is absolutely not the case that the Move cannot be grouped to the Arc and work. I have done it.

If your router is capable of having separate SSIDs for 2.4GHz and 5GHz then it is possible to keep the Move on 2.4GHz.  In any case, Sonos is capable of having some devices on 2.4 and others on 5, although that depends on the router.

But I can understand why you would believe Sonos support rather then users on here. I hope you manage to resolve this issue.

@jujiba,

By the way the Move can be forced onto the 2.4Ghz band in some circumstances, if that band has a separate/different SSID to the 5Ghz band, or the router allows a user to manually select the band for a device, either via white/black-listing a device on a chosen network segment, or sometimes through its band-steering configuration. It depends on the router features available and device configuration. 

The 5Ghz band is faster, but is not as far reaching as the 2.4Ghz band, which also has better penetration through walls etc. (Sadly my own router does not cater for me to force it onto either band as everything is automatic and cannot be configured by a user, but many routers allow it).

(edit: Ah @John B beat me to it.)

An alternative solution would be to get a One SL to group with the Arc and a Roam for out and about. Wire a Sonos device to your router (get a Boost if necessary).

Just a suggestion.