Why does my internet randomly slow down? - 2

I have a portable Wi-Fi modem that randonmly slowls down for no reason. It only has four gigs so i don't download anything or watch any videos all i use it for are facebook, skype, minecraft and instagram any idea why it does this?

Try unplugging your router from the power socket, then plug it back in. Wait for it to reset and sync back up again so that none of it's lights are flashing. That worked for me last week when my download speed slowed to a crawl for no apparent reason.