Firefox is dropping packets when downloading large files then stops

Firefox is dropping packets when downloading large files then it stops downloading the file. I'm using Windows 10 20H2

Below is what I've already tried

• Using Windows Update
• Updating all the programs in the Microsoft Store
• Updating my drivers
• Running netcut (to prevent others on the same wifi network from disconnecting me)
• Using sfc and dism scans
• Using chkdsk scans
• Having the correct amount set for virtual memory
• Running Firefox as administrator
• Making sure that under Power Management my network adapter doesn't switch off to save power
• Under Power Plan settings making sure my hard drive doesn't switch off to save power
• Changing my DNS servers to 1.1.1.1 cloudflare
• Clearing my DNS cache in Firefox under about:networking
• Deleting my cookies in firefox
• Checking my ping on the command line using the "ping google.com" command. No packets are dropped there.
• Clearing the DNS cache in windows using various ipconfig and netsh commands on the command line
• Using a VPN
  

Any other ideas?

I think the problem was caused by using a public wifi hotspot and someone else who's connected to it doing some sort of attack. It could be a man in the middle (MITM) or ARP spoofing attack. Because when I tried to access gmail with the VPN off I got an error but there was no error when I turned it on. Data that is transmitted through a public wifi hotspot travels through the air unencrypted, which is why TLS (or https://) that shows the secure padlock in the web browser is important,