Power BI On -Premise Gateway version downgrade

Hi Team 

We performed uinstall and re-installation using same name over Power BI Gateway servers first secondary and then with primary , all works well. After of it we got to know our data connection over power bi gateway cluster under app.powerbi.com are not working as earlier , we checked with every one from DB admin , Network firewall and SPN related team no tracess found and VM management we are still facing "invalid credential error " over data connection even SSO config also working fine. but UPN showing invalid user credential.