Why is my network messed up after update to windows 11 24H2

Neither Windows nor Linux distros are free of problems or issues. On the whole, my Windows systems cause me less trouble than my (Debian) Linux ones, but the 'lead' is narrow and alternates between the two.

I understand the changes were made for security reasons. But they left a lot common users in an abys of non-working devices. Machines and home networks that worked fine suddenly stopped working after an update. Yes, those settings are fine in a corporate environment with an sysadmin overlooking the changes, but they left a lot of home networks users in desperation.
Are they bugs? No, it was designed. But it certainly didn't help making the OS more popular.
As you state yourself, you were able to get things working after a couple of changes in settings.

Another thing is that machines of a couple years old (home users do not change their hardware every 5 years) didn't meet requirements.
Had that with my wife's 2018 Dell laptop. TPM 2.0, secure boot, UEFI bios, min 4GB RAM, 1GHz processor, 64GB free space, Graphics card, .... all "YES".
Processor ? .... NO, 1 generation too old. The difference is one tiny option which isn't on 7th gen Intel's. I bought her a new Asus with 13th gen processor and Win11.
Changed a regkey and converted the Dell to Win11. I got even a "green tick" on the "Windows security" icon. But for Microsoft this was already an "old PC". Actually Win11 came on the market in 2021. So at that time the 3-year old Dell was too old already to run the new OS. Anyway, I got a replacement for my 14 year old laptop now.

Blutooth is something else. I didn't experience any disturbance because of 24H2 on blutooth.

Check if there's an update of the drivers of your blutooth radio. In general Windows 11 doesn't like older drivers and may even cause BSD's.
Drivers which worked perfectly on Win10 might produce problems on Win11.
Right click on start, take "device manager" and look in "blutooth". Check the properties of the blutooth device.
Try to update the driver. When that doesn't work, delete the blutooth from the device list (if the option to delete the driver, do so).
Restart your computer, it will reinstall the driver or even take a new from Microsoft.

bluetooth no working

Hello, after updating win 11 23H2 to 24H2 several "computers" are disappeared under the "network"pane in windows explorer.

The day before updating, all computers were attached to my network and visible in windows file explorer.

After update to 24H2 they were gone!

I did see that after updating the option for media streaming were turned off.

I put The media streaming option on again, but that was not the solution.

wifi no working