On one (tablet with lineageos), Rethink was running and blocked the connection to Mozilla’s Add-on page in its firewall. Allowing Ironfox entries within firewall settings of Rethink fixed it.
On the other device (Samsung smartphone with Samsung branded Android), I first had to search within the security settings for entries that sounded like they prevent the installation of addons within an app and just temporarily deactivated them.
So, beside the already mentioned DNS cobfiguration, you might check firewall settings, if firewall is installed, or go through the “security” settings, if you are on a branded Android.
I had this issues on different devices, recently.
On one (tablet with lineageos), Rethink was running and blocked the connection to Mozilla’s Add-on page in its firewall. Allowing Ironfox entries within firewall settings of Rethink fixed it.
On the other device (Samsung smartphone with Samsung branded Android), I first had to search within the security settings for entries that sounded like they prevent the installation of addons within an app and just temporarily deactivated them.
So, beside the already mentioned DNS cobfiguration, you might check firewall settings, if firewall is installed, or go through the “security” settings, if you are on a branded Android.