Using VexIQ with Chromebooks and Online Robot Mesh Studio

I work at a school and have purchased some VexIQ robots to use with pupils in Year 7 & 8. When using their Chromebooks, and having the Robot Mesh Connect plug-in and extension installed, the following message appears on the screen whenever the pupils press on the connect button:

" says:

Unable to connect to VEX robot. Please check connection and try again."

On some of the Chromebooks, the “automatic” port detection does not work, or there is a very long delay before it does.

Whenever I connect them to my staff laptop, which I have used to upgrade the firmware on each of the VexIQ units, it always connects and works first time, but pupils are only allowed Chromebooks.

On the few that have connected, it does not always allow them to detect the sensors attached to the Vex Brain, displaying the message:

"Connect failed: readAndTest: different byte #0 expected:170 actual:255 @125/6112

Followed by “Connection lost.” shortly afterwards.

Any help would be gratefully received.

Thank you.