Hello, kenncar.
Welcome to Microsoft Community!
Before replying to your question, I hope you can understand that the community support has not been involved in the design of the product, and Microsoft's development team is not in the community at the moment. As an agent, we are not affiliated with Microsoft, and we are mainly interested in sharing possible suggestions or guidelines for users with real problems.
I really appreciate your description of the problem, and it's obvious that you have a lot of knowledge about computer issues as well. You have used some network level troubleshooting methods which are worth trying.
The slow transfer or download speeds of the Surface Pro 11, as well as the lagging issues encountered when using media apps, appear to be related to the performance of the device. For example, the RAM is not running well. So allow me to continue to narrow down the problem by sharing the following with you.
The first step is to update and optimize the drivers, you can manually get the driver and firmware installer for your Surface Pro 11 to troubleshoot unknown driver faults and maintain device performance:
Download Surface Pro 11th Edition Drivers and Firmware from Official Microsoft Download Center
Please reboot your device after the download is complete to apply the driver update. This can help us troubleshoot driver issues originating from the hard disk or RAM.
Using the above steps and the network troubleshooting you have tried, we were able to troubleshoot issues originating from the driver and the network connection.
You can also try running the Surface Diagnostic Toolkit to see if the device still has location issues. Any results are worth sharing:
Fix common problems using the Surface app and Surface Diagnostic Toolkit - Microsoft Support
If the problem persists, it is necessary to consider whether this Surface Pro 11 has a hardware performance problem.
As I am not in a position to directly assist you in debugging your device, I recommend you to contact the Surface Technical Support team for more efficient hardware service.
I share with you the steps to create a service order here:
Open the Surface App (usually built into your Surface device, or you can download it from the Microsoft Store if you don't have one) and follow the procedure below:
- Click "Help and Support" and then click "Get Help".
- Briefly describe your problem in the text box, such as "Surface transfers are slow and unresponsive", and then press Enter.
- Click "Contact Support" at the bottom.
- Select "Technical Support" and click "Confirm".
- You will see "Chat support" and "Phone support" options, please contact them during working hours, you will get one-to-one support services.
These are some of the possibilities I can share with you at this time.
I wish you all the best.
Best Regards.
Leo.L - Microsoft Community Support Specialist