Problems creating a stereo pair with amazon echo dot

[Sneddas]

Hi everyone

First post, so apologies if I’m in the wrong place. I’m wondering if anyone else has problems creating a stereo paid with echo dots?

They’re both online, on the same network and in the same room. However when I select one in the Alexa app, the other one greys out and says there’s a network problem.
I’ve tried anything. Any ideas?