@Matt Dillon, Thanks for posting in Q&A. From your description, I know you're encountering an issue with the authentication token timing out during the upload process, which is causing the 403 error. This can happen if the upload takes longer than the token's validity period, especially with slower internet connections.
Unfortunately, there isn't a direct way to increase the token timeout for Intune uploads. However, you can try to ensure that your upload speed is as fast as possible to complete the upload within the token's validity period.
For your scenario, here are some suggestions from my side.
1, Use a Faster Internet Connection:
2, Upload via PowerShell.
Here is a link with more details for your reference:
https://www.deploymentresearch.com/speeding-up-win32-apps-upload-via-powershell/
Note: None-Microsoft link, just for the reference.
You can try the above suggestion and if there's any update, feel free to let us know.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.