Diagnosis
The speaker has lost its connection to your Wi-Fi network. The flashing orange light is the network error indicator.
How to Fix It
Restart your router and modem. Unplug both for 30 seconds. Plug the modem in, wait for it to be online. Then plug the router in. Wait 2 minutes. Finally, power cycle the Era 100. The light should turn white and reconnect.
If That Didn't Work
Your speaker may be too far from the router or obstructed. Move it closer temporarily. If it connects, the location is the issue. Consider a Sonos Boost or using a different speaker as a wired SonosNet node to improve mesh coverage.
Heads Up
A steady orange light, not flashing, means the speaker is in factory reset mode. If you see that, you will need to set it up again as a new device.