Diagnosis
That solid orange light means it’s stuck in its boot-up or startup phase. It’s trying to initialize but can’t quite get there, usually because of a software hiccup or a bad connection right out of the box.
How to Fix It
First, unplug the main router from power. Unplug the ethernet cable from its WAN port too. Wait a full minute. Now, plug just the power cable back in (leave the ethernet cable out for now). Wait for it to boot up. You’re looking for it to pulse white, which means it’s ready for setup. If it pulses white, then you can connect the ethernet cable from your modem to its WAN port.
If That Didn't Work
If it’s still solid orange after that, you might need to perform a factory reset. Find the reset button on the bottom of the unit. Use a paperclip to press and hold it for about 10 seconds until you hear a chime and the light goes off. Release, and it’ll restart. This wipes it clean and often gets it past that orange light hang-up.
Heads Up
Make sure you’re using the power adapter that came in the box. The Nest Wifi Pro units are a bit picky about their power, and a different USB-C brick might not deliver enough juice, which can cause weird startup issues like this.