@razvan.luca 

Another thing to try is to delete (forget) the network on the device and then re-establish it. May need to do a reset on it to do it.

@ArcherC8 

I did that now and I get same error.

@razvan.luc

be sure the SSID is not hidden as some devices have issue with that,

try different channels and channel widths.

may need to delete and readd the device on google.

Another thing is some devices do not like certian special characters in the SSID or password. If you are using special characters, try something different.

If you get it to working, be sure to let us know what you did so it can help others.

@ArcherC8 

SSD is not hidden, it's on 2.4GHz, I reset to factory settings Nest device several times, I changed the channel from 1 to 5 with both 20MHz and 40MHz widths but none worked.

Any idea what else I can try?

@razvan.luca 

See https://support.google.com/googlenest/answer/7029485?hl=en&co=GENIE.Platform%3DAndroid

are you using WPA-2 Enterprise?

was the mini used before?
 

@ArcherC8 

No, I'm not using WPA-2 Enterprise.

I did some tests without setting a password and didn't work.

Yes, I used this device with another router. When I got this router and didn't work I sent Google mini nest in service for repair, but got the answer that is working as expected.

When I receive it from service I did a hotspot from my phone and I was able to use it.

Yesterday, after running suggested configuration, I did a hotspot from my phone again and I was able to setup and test the device. 

Last thing I did the setup on my phone using same WiFi name and password as the one configured on router, and worked... When I switched back to router wifi stopped working.