Apologies for writing yet another "sync not working" question, but so far I haven't found any question or answer that applies. I have Firefox installed on a Linux computer (FF version 96.0.3) and on an Android (Pixel 3) phone. Both are logged in to my FF account. (I was initially logged in on my computer, then, following various help articles such as [[Sync bookmarks, tabs, history and passwords on Android|this one]] this one, set up sync on the phone - and that appears to be logged in as well.) 1/ I've tried sync'ing a browser tab from the phone, but it never shows up on the computer. FF on the computer does not show any sync'd tabs. Note: On the phone, at the top of pop-up dialog from the menu > share icon, 2 icons for FF with the same user and computer are shown, along with 4 copies of the same user on a different computer, which hasn't been powered up for about a month. I have tried sharing to both the entries for the computer that is up; both result in a brief "Tab sent!" pop-up, but neither produce any other discernible result. 2/ I cannot sync tabs from computer to the phone, as there is no "Send Tab to Device" entry in the tabs' context menu. There is also no mention of external devices' tabs or history in the History menu, Manage History (Library) screen, or Synced Tabs list. And yet, Settings > Sync shows my FF account, with "Syncing: ON" and all options under "Choose What To Sync" enabled. Settings > Sync > Manage account shows both the phone and the computer as being signed in. I have tried re-starting the browser, but the behavior remained the same. The 3 extensions that are installed are disabled. Open for ideas...