Board Thread:General Discussion/@comment-32072804-20180209165324/@comment-26091666-20180216021941

The most relevant information from those screencaps is the  part, and so far the length seems to match but without having done MD5sum on the file it is hard to know if the file is as stated a proper SWF. Chances of that happening are rather slim but with MD5sum matching the chances of it being an unlikely cause would make it one in a million (or more) chance.

To verify that the file has not been tampered (even though the  matches), you will need to use FCIV. The link there is a link to Microsoft support website detailing how one is to perform such checks.

As for, that could be anything but in relation to this I doubt there is any relevance. Usually, to the far right of those lines would point to you (or developers) where the error is coming from. What I can see in that screencap doesn't tell me much and it isn't related to swf or json. The majority of the contents on KC servers are divided into four things:
 * JSON, these files usually does not have a file extension and contains various human readable data.
 * SWF, these are Shockwave Flash files and are used on ships, maps and various other assets that are already 'bundled' together.
 * MP3, these are used mainly for ship lines.
 * JPG/PNG, these are image files that were not bundled along with others into a SWF file. They are somewhat a rare sight.

Your windows firewall is unlikely to block specific assets on a minute level. The last I recall it only allows programs to either be allowed to use internet or not. Adblockers would target certain image files of a certain dimensions and/or pattern matching based on the source of the image (website) and/or the path to the image itself. So none of those two would be related. As for ISP issue, this is possible but not definite. A MD5sum test on the file, if the MD5sum matches would prove that it would not be ISP issue however if MD5sum fails (as in it does not match) would mean either your ISP is at fault or somewhere along the lines is causing the issue.

VPN may help with this but it is not a foolproof method, e.g. a public VPN would probably have their own filtering systems set up on their end in addition to your ISP (assuming your ISP has specifically blocked certain filenames or has some other low level filtering) and that would only compound issues.