I cannot get BBC iPlayer to run in Firefox (57.0.3 64bit for macOS) (MacPro, macOS 10.13.2) The behavior is as follows: I log in with my BBC account. Sometimes BBC.CO.UK loads fine. Sometimes the images do not load. There doesn’t seem to be any pattern (that I have noticed) to when it does or does not load. When going to iPlayer, the images on the iPlayer page & on various channel pages also occasionally fail to load - or sometimes do. When choosing a video (or live stream) to view, the “play” icon or the screen image itself will feature a rotating icon and after a time, the video panel will hang, remain blank, or will display “This Content Doesn’t Seem to be Working”. Right-clicking the player window shows the numbers "2.16.27.1838333.u.x”, “b09kknkx" and "Error:1068". Downloads using the "BBC iPlayer Downloads" app work normally. In the course of troubleshooting, I have tried normally, with extensions disabled, and Safe Mode. Have tried clearing cache/cookies. I have rotated through the adjustments for the plugins (which are only OpenH264, Flash, and Widevine). I have “refreshed” Firefox and I have tried running with a brand new profile. I have tried restoring an older (pre-Quantum) from my Time Machine backups. Flash is up to date (28.0.0.126). Currently running on a reinstalled copy of 57.0.3 on a clean profile with no extensions, and with flash permissions set to Always. None of this changed the basic behavior I have been seeing as mentioned above. It should be noted that iPlayer works normally in Safari with default settings on the same machine & internet connection. And iPlayer works normally on my phone in both Safari-iOS and Firefox-iOS from my home network and while connected via cellular. Seems like it should be something simple I’m overlooking. Though I can use Safari to view iPlayer items, I’d like to solve this as well. Cheers and thanks so much for taking the time to read.