For some reason I can't connect to the XLN servers via their online installer. I can connect to the internet, any other site, and other servers for downloads...just not theirs. All anti-virus protection is turned off when I try. I unzipped the file using the native windows unzip option, per their instructions. I also tried running as an administrator.
 
Their support has not been helpful, so I was hoping someone here might have encountered this problem and found a solution.

Hi, Craig.
My XLN installer works as expected on my laptop.
Just logged in, and it is downloading an update as I write this.
Sorry to be of no help.
I am on 1703 on my laptop, by the way.
All the best.
Edit: On my studio pc (1709) I had to re authorize AD2, but that is normal.

I had this problem temporarily and it cleared itself up the next day. I have no idea what happened. I was beginning to become concerned.

No problems here. I just ran the installer as I write this, and the XLN installer updated itself, and then updated the program. 

Can you bypass the installer and go directly to their website via your browser?  I had to do this the other day after updating W10 because it said my installer was out of date.  I updated from their site and all was OK after.

Possibly a PC reboot ?

I installed the XLN stuff earlier this week. Initially I had problems with their website, which kept displaying error messages. I ended up moving to a different computer to download the installer. Back on the DAW computer, the installer ran ok without any issues. The installation took a very long time though.

Just updated the XLN installer, Addictive Keys (free version) and AD2. All went as expected. Shut down and restarted the installer, everything looks OK. Running Win10 v1703.

Craig, you may have to log into your XLN account on line, and re download the installer.

I had sort of the same issue where it hung up as I was trying to update the installer, got half way through dowload and just stopped. I waited about an hour before giving up.    So I quit but now I had nothing! Clicking the XLN icon just would go round and round. Lucky I still had the last installer in my download folder. 
I ran that and this time it updated ,, very slowly. It took a few hours to update everything.  
It might be because of the update to both the on line installer and AD2 that the servers are taxed out. 
 
Bonus was I clicked the Register tab and found I had 3 kit pieces I hadn't claimed and a whole kit! 
Turns out I got four kits, 1 with Professional and 3 with Splat. So I forgave XLN for having a  buggy update interface.