Hello @kristian bacalso ,
Please check in the windows registry for LanManWorkstation in:
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters]
And change the key "AllowInsecureGuestAuth" to 1
The other option is through GPO, if you need to expand the change to multiple machines:
GPO path: Computer Configuration>Administrative Templates>Network>Lanmanworkstation> Enable insecure guest logons = Enabled
Hope this resolves your issue,
Best regards,