So after spending the last 40 minutes trying to return to the game I was getting this error and much like nearly all the threads here the 'documented' fix just doesn't do anything.
So keeping this simple, as I am blessed with being able to run some enterprise level firewalls I had a nose into what might be going on (being a paid nerd has it's advantages). Here are my findings.
1) The manual patch manifest download has a poor reputation which was silently triggering security software. As to why, you'll have to ask big old Beth. The link I'm on about is here -
http://launcher.bethesda.net/Bethesda.net_Launcher/Bethesda.net_Launcher.patchmanifest
2) Out the box IPS was freaking out and dropping packets every time the launcher tried to do something - possibly related to the above.
3) SSL/TLS inspection also disliked traffic from the launcher, though that part is a bit beyond my paygrade.
Whatever Beth have down as a 210 error, these things were definitely triggering the launcher to send me on a wild goose chase.
Now, not everyone has this big box of tricks but thats not to say that "isp provided" routers don't have some built in basic protection that market themselves as keeping you secure on the internet, we've all seen the adverts.
Certainly pairs up with this stuff happening after a patch.
Just thought I'd share, enjoy.
V