Oh man, if you only knew the things I've done to troubleshoot this issue. I thought of the host and listening port early on in this journey, unfortunately. I used to be a network engineer so my networking foo is quite strong. My java troubleshooting skills, however, not so much. Just to give you an idea of how badly this was driving me mad, here are just a few of the things i/we tried over the last few weeks. (After the obvious tshooting got me nowhere) :
1. I turned widows firewall logging up all the way and saw the traffic being allowed through. I disabled windows firewall altogether, just to be sure.
2. I worked with my IT dept to disable pieces of the kaspersky virus/Malware software we use, until all of the protection mechanisms were disabled and it still wasn't working. Still not fully convinced, I talked them into completely uninstalling the software on my laptop, temporarily of course, just to be sure it wasn't hijacking my connections.
3. At this point, I was completely baffled. I was so sure Kaspersky was going to be the culprit. I thought maybe runwar or undertow stored some settings in the windows registry or something, so I created a new windows user, downloaded Commandbox fresh and still had the issue.
4. Before all that, I uninstalled all my Javas and reinstalled only JRE 1.8.101. Tried 32 and 64 bit versions. But it didn't make sense that it was java to me.
5. I did a system restore back as far as I could go, July of 2016.
I was ready to reinstall windows but I thought surely there was another windows user who would run into the issue sooner or later. So I decided to give it a week or two.
I'm just glad my team decided to move away from SVN and move to git. I never would have found the disabled "Null" device driver had it not been for git refusing to load.
The only good thing that came from this fiasco is now I have a really evil way to mess with a coworker if s/he ever leaves her pc unlocked for any amount of time. (Unless she uses git, that is 
) really though, I learned A TON about command box,runwar,java and undertow through all this. that's a plus.
I can't tell you how great it is to see the directory structure of my server root appear in my browser now when I start a server in commandbox. It had been so long!
Take care and thanks again!