Internet wifi/direct connection drop everytime I attempt to download anything

Let me start by saying I pay for 300 and get 350 download and up to 25 upload. When I am connected to the internet surfing the web I am usually fine, streaming videos fine, accessing apps fine, sending messages over wifi fine. DOWNLOADING anything on my pc mainly a game the signal drops within 30 seconds of me pressing download. It comes back after about 2 - 4 minutes. I used to have a problem where it dropped consistantly every hour on its own but that seems to have gone away. Now i am plagued with this anti-download internet. Can someone help or attempt to explain what might be wrong.

I already did the following:

1. reset my modem a million times,

2. contact tech via live chat who thought the issue was that my boot file was outdated and they sent a signal to "update it" and acsked me to unplug everything and plug it back,

3. increase my firewall and made sure I have no more than 5 devices plugged/connected to the modem,

4. moved modem location in home,

5. reset a million more times

Send help, pls