1. I installed the CA certificate that was used to sign the certificate of my own Sync-1.5 server. 2. I verified that Firefox can connect to my own Sync-1.5 server without refusing the SSL certificate. 3. I used about:config to set identity.sync.tokenserver.uri to the address of my own Sync-1.5 server as described in https://docs.services.mozilla.com/howtos/run-sync-1.5.html 4. I signed in to my Firefox Account using Firefox->Settings->General->Sign in. 5. I navigated to Firefox->Settings->General an clicked on my account. Firefox tells me that I am logged in, but never synced 6. I click Sync now. Firefox still tells me that it never synced. Android->Settings->Accounts->Firefox tells me that it synced. This was all done on a fresh installation of Firefox. The logs of my webserver show no connection attempt from my device. Syncing my desktop Firefox (FF 45, Linux) using the same account and Sync-1.5 server works fine. Firefox 46.0.1. Android 5.1, Samsung Galaxy Note 10.1 GT-N8020

   adb logcat | grep FxAccounts

   E/FxAccounts(11682): javax.net.ssl.SSLException: hostname in certificate didn't match: <my-sync-15.example.com> != <www.example.com>