Your unifi port is 5mbps, when no people is consuming bandwidth, meaning you are the only one who using internet, it won't cause problem, but if a person joins the connection and starts loading videos/downloading stuffs, your 5mbps bandwidth is being distributed to your gf's iphone and causing internet congestion, thus increasing latency of your connection, in order to avoid this from happening, set QoS in your router so your dota can preserve certain amount of bandwidth which prevents latency from increasing when someone is using your connection.

Hope it helps.

QoS is quality of service and it is readily available in your router, go to your router setup page, mostly 192.168.0.1 or 192.168.1.1 depending on your router setup, then find QoS setting and apply the ip and port, for more info you can try to find in lowyat network section. I believe someone had asked before in network section.