Hello guys,

I have 2 internet subscription: Unifi (100Mbps) & TIME (100Mbps).
Both are using Dlink DIR-850L and both connection is at different place.

What I noticed:
On 2.4GHz WiFi : The connection maxed out at 50Mbps
On 5.0GHz WiFi : The connection can reach max 100Mbps
Why does this happen? Theoretically on 2.4GHz N connection it can reach max speed too.
Do you guys have this problem too? 

Blacktubi and the rest already explained pretty much eveything from what i read. You need to understand wireless n is much slower then wireless ac but unfortunately at the same time the wifi radio signal of ac is much smaller. There no way around it but to fork out more for a better ac router.

Forget about believing what is advertised at the box claiming wireless n speed at 300mbps, those are theorical speed inside a lab where there zero interference. You might say get 200+mbps using wireless n at most in real world scenario if both the router and your end device also capable to receive and transmit at 300mbps, which is usually reserved for flagship devices.