I created a publishing site in SharePoint online and provided unique permissions. Two users (one internal & other external) provided full permissions. Internal user can access site but external user can't access site. Can anyone please assist what is the problem ?
Whether the user gets an email and login using any Microsoft domain email account (hotmail.com, live.com, outlook.com or another Office 365 account)?
If the user authenticates with Google or Facebook account without Microsoft or Organizational account, he has to create a new Microsoft account before accessing the SharePoint web site.
Refer below article to setup external users in SharePoint:
Thank you for responding to my question.
The problem is solved now. The problem was that there was limitation of external domains in site collection feature. If want to limit external sharing of site, follow below steps:
1- Got to https://portal.office.com and click on Admins.
2- Click on Sharepoint in Admin Centers.
3- Click "More features" in left side.
4- Click "Open" on "Classic site collection page" in right side.
5- Select the site collection of the site and click on Sharing.
6- Go to Site Collection additional settings and add gmail.com (if there is already domain added, put space between two domains).
7- Click save button.
Now access the site using external user account.