

On average it takes 18 months to grieve a loss. Divorces are no exception.
I’ve gone through 1 divorce and some long term relationship breakups, pretty close to when loved ones die.
Eventually it’s replaced by new automated defenses and behaviors. Hopefully not too unhealthy.
Here’s my testing recommendations
Testing methodology
To get consistant results, use a consistent method of test. If you’re downloading a large file, always test by downloading that same file from that same source. If you’re using a speed test service, use the same speed test service with the same server. If you’re using a tool like iperf3, always use the same tool against the same iperf server.
Potential issues
Networks can fail from hardware issues, software issues and infrastructure issues. Since you don’t control 99.9% of the infrastructure if the internet is involved, lets leave that for the last option.
Hardware Issues
The hardware involved you control are mostly your NIC, and your Remote Connection. For wired ethernet at home, this is likely a physical ethernet port on your computer on one end, and another physical ethernet port on a switch/router/ap provided by your ISP.
Testing Wired Hardware Issues
With these three you can figure out what device is causing the problem.
Testing Wireless Hardware Issues
The hardware involved is the wireless NIC in your computer, the environment your wifi signal is in, and the wifi AP. The steps are much the same as testing for a wired issue
Software Issues
The issue could be software related. Something like the drivers running on your laptop or connection point.
Testing Computer Drivers
You’ve already done this for your computer by dual booting. This proves the issue is not driver related, since the problem persists with two different sets of drivers.
Testing Connection Point Drivers
Testing Computer Configuration
Your network settings could be misconfigured.
Infrastructure Issues
If your home network is more sophisticated then an ISP provded router/switch/ap combo connected to everything over wifi and ethernet, theres more devices to troubleshoot. But if you have something like this, you probably already know what you’re doing a little bit and wouldn’t be making this post. But who knows! Re-run the process isolating each device and replacing it with something known good to identify whats causing the problem.
As for the internet, it’s not a stable and safe place. Speeds vary drastically day to day. Internet weather happens and partial outages occur regularly. Don’t forget that the service your using to speed test could be the issue itself. It’s another component to isolate and test.
Process
Use the above steps to identify what device is causing the problem, and if its a hardware or software issue. Hardware issues are mostly resolved by replacing devices, while software issues are resolved with software updates and configuration changes.
Good luck and god speed!