I assume you're using FTM2017 (if not, please read the rest of this discussion which explains that earlier versions can no longer connect to Ancestry), and that you've confirmed that you can access the internet normally using a web browser and you can use the Ancestry site.
I've just checked and I currently see this same problem, and I also experienced it yesterday for a while. I'm assuming it's an even more severe instance of the Orange or Red sync weather alerts, in which the sync system is down completely, so it should hopefully resolve itself in time. It's likely to be associated with the continuing problems at Ancestry with their server upgrades, which were meant to be completed by the end of May, but in my experience both the Ancestry site and the FTM sync seem to be worse than ever, with performance issues and errors, and frequent Orange and Red sync alerts.
Even so, it may be worth shutting down FTM and restarting your PC, as I've had this as a "glitch" in the past, and you could even try uninstalling then reinstalling FTM, but I suspect if you just wait and try again later, it will eventually recover.
Edit: I've just tried again and, as I suspected might happen, the FTM sync has recovered and is now "Green" for me. However, it's a bit disappointing that it's still showing the "Welcome back to green" fanfare that hasn't been updated since it was introduced two weeks ago :-(