When I choose "Send tab to device" on my Firefox desktop for a tab, it can take minutes if not hours for it to appear on my phone. On different occasions, I've tried sending a tab from my Linux desktop and from my work Macbook to my phone, with the same results. This makes the feature somewhat unusable for me—I generally need to view the tab right away. Device specs: - Phone: Nexus 5 running Android Marshmallow - Computer 1: MacBook Pro 2015 running macOS High Sierra - Computer 2: A desktop running Ubuntu 18.04