Upload and Download troubleshooting

Hi,

I have an Nighthawk Router AC1750 R6400v2

I am trying to troubleshoot a large file upload and download issue. I have called my ISP and they did not indicate there is a limit to data transfers.

I have fiddled with settings as I read things I try this or that and I might have caused the prob;em myself. I am trying to trouble shoot why I have this problem transfering large files anything large 1g for example I can not upload. If I send to weTransfer for example it always stops uploading at 45mb if I try to download a large file it stops at somepoint and does not download anyfurther. Any idea where I might find a setting that is messing up my large data transfers?