It only accesses 'google.*' sites.

Originally it only had a permission for 'google.com' but then it failed on 'google.co,jp'

https://discourse.mozilla.org/t/support-igoogle/12480/19

It is not practical to list all google TLDs like 'google.com, google.co.uk, google.co.jp,' etc

The permission API at the moment doesn't have a system to include a wildcard in TLD and that is the reason a general all sites permission had to be used. I had asked (11 months ago) for a better API but it was not accepted.

https://bugzilla.mozilla.org/show_bug.cgi?id=1362849

Which version did you try?
Please post all support questions to the support page.

Update: v2.0 I tested all its functions with FF54.0b6 and there were no errors.

Connection error relates to internet connection.