My LAN speed is lower than expected

[ArkLade]

Hello
I'm a bit of a network noob and having some problems with internet speed.

I recently moved to NJ and got Optimum 400 mpbs internet.
I am using Arris Surfboard DOCSIS 3.0 (has one gigabit port) Modem and Surfborad AC1750 Wifi router (up to 1750 mbps).
On top of that, I am connecting my desktop with Powerline network; Tp-link AV600 (up to 600 mbps).

I am pretty sure my equipment installation is all good such as cable condition, distance between desktop to router, and power line connection.

Issue 1: I ran internet speed check for desktop and I only have 30 mbps for download and 35 mpbs for upload. Wifi for my Iphone is bit lower. I was expecting more like 200~300 mbps but why is this happening?

Issue 2: Desktop Local Area Network speed is 100 mpbs not 1G. Does this mean that maximum speed between desktop and router is only 100M? why not 400M? If do, what is the point of using 400M internet?

Issue 3: I've searched and many people have LAN speed of 1G not 100 M. Should I have 1G or 100M shown on LAN? If do how do I change?

Thank you so much guys and let me know if I am missing anything.

 

[Gabriel Pike]

For issue 1 are you connected wireless or wired? If wireless what channel 2.4 or 5 GHz? Wireless in a 20 MHz channel is typical 30-50mbps on 2.4. 40MHz on 5 GHZ typically will get you up to 300mbps. If your device has no 5GHz WiFi Card you will never see more. Likewise if your router is only 2.4GHz. Another possiblity is if you have close by neighbors, your wifi could be getting interfered with by another signal.

For issue 2 the interface on either the desktop, or the router is only 100 base-t this means that one of these will only negotiate to this speed. To get gigabit link they both must have gigabit ethernet adapters.

Issue 3 falls under issue 2.

For a test, plug directly into modem and check speeds. This eliminates any trouble with routers. If the speed is correct at the modem then the problem lies in your routers somewhere.

 

[DelJo63]

The whole Internet operates (speed wise) just like the 'weakest link' in a chain.
In the path from your device to the site you wish to access, the slowest adapter will always be the limiting factor.
So your device adapter, your AP or Router and sometimes your ISP gateway will play this game.

Additionally, while a device might be rated at say 100mb, real life TCP max's out at ~70% of rated capacity.