Cannot use offline ERPNEXT that is locally host

I basically followed the guide of Dcode (GitHub - D-codE-Hub/Guide-to-Install-Frappe-ERPNext-in-Ubuntu-22.04-LTS: A complete Guide to Install Frappe Bench in Ubuntu 22.04 LTS and install Frappe/ERPNext Application) in installing erpnext. The versions I installed as it appears in my “About” are the following:
ERPNext: v13.34.0 (version-13)
Frappe Framework: v13.33.0 (version-13)

My setup is locally host in my laptop. Problem is when I disconnect to the internet I cannot use erpnext.

Are you using it with a domain or localhost ???

@JTY activate developer mode .

@JTY This is correct. Took us a while to figure it out