- Click in the  Administration → Config access menu in the Web/REST interface section in the row of the access configuration on Administration → Config access menu in the Web/REST interface section in the row of the access configuration on and check the checkbox Activate HTTP. and check the checkbox Activate HTTP.
- Click on SUBMIT . 
- Click on ACTIVATE PROFILE  . .
Information regarding the authentication via user or client certificates are available in the Online Help in the Protected access to the web interface of the router section.