Steam games hogging bandwidth

[Wade1234]

A friend of mine has fios gigabit (G3100 router). Speedtest on desktop runs normal 700Mb/900Mb. The second he opens any game (only on the steam service), his speedtest immediately goes to 5Mb/0.8Mb. I know this isn't computer related, because he just bought a new pc a few weeks ago and it was happening on that as well. He's rebooted the router, tried WiFi, hardwired with cat6, reset router to factory settings. I've read a few threads of people with exact same issue as him, and there wasn't a fix. He's tried turning the firewall down to low on the router itself because someone mentioned DDoS protection having a bad interaction with steam. What router settings should we be looking at? I'm clueless on what to do to help him.

[Cang_Household]

It would be easier if your friend directly posts here, instead of doing a message relay. Every Fios customer directly has a Forums login through their Single Sign On ID.

Don't change the Firewall level to Low, as that would make the network vulnerable to malicious attacks.

I am wondering could it be the Steam is pulling upgrades and saturates the network connection, thus leaving the browser speed test with little to none bandwidth. If the friend open up the Task Manager > Performance, does the friend see the speed of downstream and upstream?