The only way to get Era 100 on Sonosnet is by using the Sonos Combo Adapter. Without it Era 100 is relying on my home wifi to connect. My wifi isn't as stable as it should be, therefor my Era 100 is suffering from the occasional dropouts. That's saddening. Ever since I've been using Sonosnet in combination with fixed IP addresses in my router I haven't had any dropouts. That's since about 10 years!
I think it's a grave mistake Sonos eliminated the Sonosnet wireless option from Era 100. I'd like it reintroduced very much.