And the laptop is not (both wired.)
It sounds like your modem has WiFi or it's connecting to some other hotspot, so turn off WiFi on the laptop to be sure it uses your wired connection.
I have a Dell XPS l502X laptop, having slow download issues with wired connection to ASUS RT-AC87U. Only about 80Mbps on a 200Mbps connection.
I get close to 180Mbps with the laptop connected directly to the modem on a 200Mbps connection using the same cable.
A desktop wired connection to the router does not seem to have the same issues-expected download speeds 180-200Mbps.
So in summary.
Laptop wired to Modem->No issues.
Same laptop wired to Router-Slow speeds
Desktop wired to Router no issues.
I have tried switching ports on the router, updated ASUS to latest firmware. I also have the latest kaspersky Internet security and windows 10- Not sure if it can throttle speeds based on wired to router vs modem.
Another interesting observation is when i try to login to router settings page with the laptop wired, it leads me to 'mediacom' login instead of ASUS router. The wired desktop leads me to appropriate asus router page.
Another thing I noticed is the desktop is slow similar to Laptop when in command prompt ipconfig I see connection specific DNS suffix is : hitronhub.home
It's normal when connection specific DNS suffix is : empty.
I was able to powercycle modem, router, desktop computer and connection specific DNS suffix is empty, Internet is fast and can access my router login page. But this powercycle does not work with the laptop