Backup the config first so you can restore if something goes wrong. Here is what I did.
Right click on the WAN settings page for Internet click on Inspect/inspect element. You'll see the html code on the bottom of the browser. Ctrl F and search for
fieldset. You'll most likely see
two entries with <fieldset disabled=""> or <fieldset disabled>. Change both to just <fieldset> and then click on the delete button at the end of the page. Then follow the instructions by tellanand in the previous page.
This is basically step 2 of the above process.