I don’t see that you’re going to get a lot of help from the network statistics page. A lot of things can kill the file upload. The quickest way (to get help) is to upload the file if you can (to the forum for someone to check out).
And by upload the file, he means upload it here so that forum members can determine if the problem is with the file.
File size has very little to do with whether it will upload. It’s the amount of time to execute the cut/engrave that is often the issue. Then there are little quirks within a file that can stop the processing.
Yes, the things you need to look for are listed in the tutorial below, along with a few other things that didn’t make it into that one, but are scattered among the other tutorials below it.
That should get you started. If you created the PDF file, it should be fairly quick to spot the potential problem areas from what you did to create it.
If you didn’t create the PDF, good luck. Hardest thing to do is try to fix someone else’s work when you have no idea how they created it, or what program they used. You’re likely better off just recreating it yourself.