Laptop not always accessible in home network

I have 2 desktops and 1 laptop at home. All 3 are joined in a homegroup, and all network and sharing settings are selected properly. All 3 computers have same windows accounts (passwords), same programs and same internet security.

The 3 computers show up in the network folder and can be accessed from any other computer.
However access to the laptop is often denied, by error message 0x80070035 "network path not found"

From the laptop, each desktop is always accessible, no matter who is signed in.
From the desktops, the laptop is often not accessible (error message)
If nobody is signed in on the laptop, access seems to be ok.
If someone is signed in, quite often the network error does appear.
Very strange

Does error still produced if you disable the Firewall of Internet Security?

Yes, disabling the firewall makes no change.
WiFi network is set on "thrusted". Selecting "local network" does not change anything neither.