Hello Joebar1,
We understand that your internet speed is very low and fluctuates dramatically. The following steps can assist you with getting the best reliability and performance from your network:
Recommended settings for Wi-Fi routers and access points
If the issue persists, the following steps may be helpful as well:
"1. Check Wi-Fi recommendations or use Wireless Diagnostics
If Wi-Fi issues are detected on your Mac, you can view the issues and suggested solutions. Click the Wi-Fi status icon 
in the menu bar, then choose Wi-Fi Recommendations. Wi-Fi recommendations aren’t available for enterprise networks or Personal Hotspots.
You can use Wireless Diagnostics to solve problems with a network you’ve already set up.
2. Check your Wi-Fi connection
If you usually connect to the internet using a Wi-Fi network, make sure you’re connected to the Wi-Fi network.
If you’re connected to the Wi-Fi network but you can’t connect to the internet, there might be a problem with the network’s internet connection. If you set up the Wi-Fi network using an AirPort device (such as an AirPort Extreme), you can get information about the device and its internet connection by using AirPort Utility. For more help while using AirPort Utility, choose Help > AirPort Utility Help.
3. Check the status of your network connections
You can check your settings and the status of each network service, such as Wi-Fi, Ethernet, and Bluetooth, in Network settings.
On your Mac, choose Apple menu 
> System Settings, then click Network 
in the sidebar. (You may need to scroll down.)
The network service you’re using should have a green indicator and the word “Connected.”
To view more information about your network service, click to select it.
4. Check your internet service
If all of the above are set up correctly and you still can’t connect to the internet, call your ISP. There may be a temporary problem with the service.
More details here: Solve internet connection problems on Mac
Best regards.
