RT-AC68U LAN speed problem/wireless speed problem

[jsamples01]

Hello. New casual user looking for guidance.

Asus RT-AC68U with FW 3.0.0.4.378_3813.

I am having huge issues with LAN speeds, and sometime wireless speeds and connectivity.

I have a W7 PC and Xbox One hardwired to the router. Router is CAT6 wired to brand new Zoom 5341J cable modem the I bought to avoid TW rental fees and hopefully take advantage of DOCSIS 3.0 speeds and connectivity soon. Currently I'm on the standard TW 16U/1D plan.

Using testmy.net I've noticed that there's a connection issue. DL speeds range anywhere from as low as 4Mbps to the rated 16. But they normally stay within about 12-16Mbps. Upload speeds are horrendous. There normally run HALF of the rated 1Mbps, and often times are 100Kbps-300Kbps.

When I hardwire the PC directly into the cable modem, it's top speeds both U and D consistently. So it has to be something going on in the Asus Wireless Router that is affecting my speeds.

I took it to Geek Squad. I know more than them. They hooked it up and did some sort of file transfer test on the LAN ports and said "they're working." I know they're working but for some reason they're not working well!

Is there any good free network diagnostic software that I can try that will diagnose LAN issues specifically? Any advice would be appreciated. Thanks.

edit: I also reset the router's settings back to Factory Defaults, and cleared the NVRAM.

 

[RMerlin]

Turn off your modem for 10 minutes and turn it back on to fully reset the connection with your ISP. This is necessary with cablemodems when moving them between two different clients (i.e. between a new router and a computer).

Also replace the Ethernet cable between the modem and the router just to be safe.