Does your phone connect OK to other sources of Wi-Fi such as a coffee shop etc @Pio83 ?
There is a diagnostic tool in your Samsung Members App under the GetHelp button and diagnostic.
A Samsung Experience Store or Samsung Service Centre can take a look at your phone.
Current Phone > Samsung Z Fold³ 5G.
It may be worth sending an Error Report through to the Software Team if you believe an update started this issue, @Pio83. You can do this by recreating the issue (waiting for the Wi-Fi to drop out) and then heading to the Samsung Members app > Get help > Error Report > Ensure 'Send system log data' is ticked > Include a full description of the issue. The Team will then be able to take a look into what is happening within your phone and advise further. 🙂