Chromebooks / Multiple Sign in / Certificates

[ModeratelyGruntled]

Some background:

 

- We have trusted authentication set up to allow users to sign into Google resources (Apps and chromebooks) using their Office 365 identity.

- Our Local authority manages all of our wireless SSIDs and Internet provision which includes Smoothwall.

- We have a public (no authentication) SSID and an 802.1x SSID

 

The sign in process works fine on the Public SSID, which doesn't require any certificates.

 

With the 802.1x SSID, devices connect to the network but do not reach the login.microsoftonline sign-in page, eventually timing out with NET:ERR_CERT_AUTHORITY_INVALID

 

Question:

 

Am I right in thinking that that Multiple Sign-in will be disabled because Smoothwall with have SSL inspection on? Is there a way around this if so?

 

Does anyone have a similar configuration that can provide some more information?

 

Many Thanks!