Google nest mini advice

Hi all,

I'm fairly new to HE after defecting from HC2 (well half way).

I just found a couple of nest minis in a junk box in my office. I'm interested in running tts announcements/notifications. So far so good. I have a C8 (wifi) that I'm populating bit by bit as I figure things out, and a C7 (ethernet) as a test bed.

The mini adds ok to C7 (after a few trys) and works great. But It will not add on the C8. Both are on the same wifi network and are even in the same room... but no joy and nothing in the logs.

Anyone have any ideas?

Many thanks
Sean