20.04 NetworkManager How to autoconnect to specific hidden Wi-Fi network?

[transit-y]

I have exactly the same problem!

I have 2 laptops, 1 Dell and 1 Lenovo. Both were recently upgraded from 18.04 to 20.04. With 18.04 both were able to automatically connect to the hidden WiFi whenever it was available. After the upgrade to 20.04, the Lenovo can still connect automatically to the same hidden WiFi - the Dell cannot and every time I have to connect manually. The settings are exactly the same in both laptops and the same as they were in 18.04.

This is very frustrating and since the Lenovo does not have this problem, I take it that it is not a matter of 20.04 not allowing automatic connections to hidden WiFi networks in general, but a bug in the Dell's 20.04 installation.

Can anyone recommend a solution?

[Edit after coffecat's suggestion - thanks coffecat]
Specifics on the Dell hardware:
lspci -nnk reports: BCM43142 [14e4:4365] (rev 01), Kernel driver in use: wl, Kernel modules: bcma, wl
dmesg | grep wl reports: BCM4365 802.11 Hybrid Wireless Controller 6.30.223.271 (r587334)
/etc/modprobe.d/ contains a blacklist-bcm43.conf file which includes b43, b43legacy, ssb, bcm43xx, brcm80211, brcmfmac, brcmsmac, bcma

After restarting the Network Manager service, journalctl entries of the 2 laptops are similar up to the point of "supplicant interface state: init -> starting". After that,
the Lenovo reports: sup-iface[.....]: supports 5 scan SSIDs
whereas the problematic Dell reports: sup-iface[.......]: supports 1 scan SSIDs [Not sure if this has some significance for the problem the Dell is experiencing..]
then both laptops report that the supplicant interface enters the "ready" state

Then the Lenovo finds that there is a profile for hidden wifi networks and actively scans for them [device (wlp5s0): wifi-scan: active scanning for networks due to profiles with wifi.hidden=yes. This makes you trackable], finds the hidden SSID and connects - everything OK.
The Dell just sits there happily, only reporting that the Network Manager has started [manager : startup complete]. It does not seem to recognise that there is a profile for hidden wifi networks. I guess this is the "bug" I am experiencing in the Dell laptop.

Is there some other information that I can post to help resolving this?

[coffeecat]

Moved to own thread from here. Please start your own threads.

Unless you give specifics about the wireless hardware on your problematic machine, no one is likely to be able to help. Have a look at this sticky: https://ubuntuforums.org/showthread.php?t=370108