Vostro 5620 suspend behaviour broken after BIOS update

Hello,

I've happily owned a Vostro 5620 laptop for almost 2 years.

My typical use of the Vostro has always been heavily relying on suspend mode, e.g. :

- lid closure is set to have no effect

- I tipically suspend with the power button, and once I reopen the lid the laptop is tipically ready in a few seconds

- If I leave it closed for a few hours, the laptop takes a minute more to wake up, but apart from that no difference from previous point behaviour

- I rarely reboot the computer (maybe once every 10 days)

I usually keep the laptop updated with Windows Update and Dell Support Assist.

On 1st April I installed 3 upgrades with Dell Support Assist, among which there was a BIOS update to version 1.33.0 (sorry the screenshot is in Italian)

Since the above update, the suspend behaviour is somewhat broken:

- when I suspend with the power button, if I reopen the lid in a short time (say 5 minutes) the laptop behaves OK

- If I leave it closed for more (e.g. 1 hour), next time the laptop boots in diagnose mode; at the end of the diagnosis operation, it says it didn't find a solution, and then it boots normally. It tipically takes around 5 minutes (not including the OS loading, which is quite heavy in general for my setup - lots of software installed). Of course all the programs I had opened etc. were terminated "abnormally"

Solutions tried:

- reloading default settings in BIOS

- checking/fixing  power options (don't know why, after the BIOS update, initially the hard disk deactivation was set to happen after 1 minute of idle...)

- running Windows Update and Dell Support Assist every day since the 1st of April

Product Id: 00355-60802-08967-AAOEM

OS: Windows 11 Pro x64 25H2 build 26200.8117

HDD M.2 upgraded to 2TB since 6 months - never had issues

RAM upgraded to 32GB since 6 months - never had issues

Can you help me?

Thanks!

Andrea