In my case, it was about setting up a firewall, let me tell you what I had in mind:
I checked the Windows firewall and saw that there was an exception for TFS. But that was not enough, why? See the following image:
As you can see, TFS was excluded, but not for Public
So, you can check the "Public" box, or you can change your network location from "Publish to Home" or "Work", go to: "Control Panel"> "Network and Sharing Center" Change your location Networks Now you can simply use the Windows accounts that you have, and they will be definitely accepted.
Overview. What is the default username and password again?
Assumption: you are using TFS on the local network, your own server is your own client!
Short answer: as an easy way, you have to create a Windows account, enter it in TFS to grant permissions, and then you can log in to this account from anywhere in your local network.
Long answer:
Step1: create one or more Windows accounts, do it, go to the control panel → User Accounts → manage another account (create another account while you can use an existing account) → Create a new account → Give it a name
- You may need to select an administrator.
Then select the created account → Create password
Step 2:
Go to the web portal for VS TFS 2015, click on the team members (or click the gear icon in the above line and go to the security tab) Add → Add user or user group → Browse for the account you have already created or simply enter it, to add it.
Step 3:
Go to the web portal for Visual Studio Team Foundation Server 2015 through a web browser at the following address, for example http: // user-pc: 8080 / tfs (which you can find in your VS or TFS), like 
then you are faced with a dialog box that asks for the username and password, give the credentials that it asks for based on the Windows account you created, if everything is okay and there were no problems with the firewall.
Finally:
You can see several users on the Windows welcome screen, which seems annoying so that windows do not display them on the welcome screen Go to computer → Management → Local users and groups → Users double click on each of them and delete their data member (which is set by default By Users) Thanks to IT