No, you cannot.  You could connect them via the USB-Ethernet adapter, though.

Is that ethernet directly to each other or to the internet?

They’ll connect to your local network, though also to internet via your router. 

Hi ​@Smarthomefanatic 

Welcome to the Sonos Community!

There are no known issues with stereo pairing two Era 100s together. 

Where did you read that there was, please? I suspect any such reports were probably resolved by either rebooting the router or the controller involved.

Are you personally having trouble doing so? If so, I recommend you get in touch with our technical support team who have tools at their disposal that will allow them to give you advice specific to your Sonos system and what it reports.

I hope this helps.