Contact person: C# .NET (Entity Framework) App, Network Error in VPS Migration and Troubleshooting

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Location: Hyderabad, India

Budget: Recommended by industry experts

Time to start: As soon as possible

Project description:
"Hi,
Iam using a C# .net (Entity framework) app as sms dashboard from 3 years. Its working fine.
As my usage decreased, I need migrate server to reduce vps costs.
My present server is Windows Server 2016, SQL 2016 (Web).
Iam trying to migrate this to a new vps Windows Server 2016, SQL 2016 (Express). (Data is not big, SQL Express will be fine for my usage.)

What I did:
# Created new vps. Migrated all files from old vps.
# Updated [login to view URL] file.
# Restored database from old vps DB backup.
# Updated IIS settings, Added websites, Bindings, Updated Application Pools.
# Updated firewall to open SQL ports.
# Checked SQL Configuration Management settings.

When I try to open website, website index page (dashboard login page) opening.
But, an error showing (top right side) " Network Error please contact administrator ".
And can not login using my login details, showing same error when I try to login to my app.

( When I try to check this error online, seems connectivity or security permission error. )

I need you to check and update required things to make my app work. (No error and user to login successfully.)
# And you will give me details that I missed. (So that in future I can do migration my self when required.)

Ideal Skills and Experience: Windows Server, SQL Server, C# .net, Entity Framework, Server Admin etc..

Logins will be shared in DM. Need this to be done on priority immediately. Budget is not much. Please bid accordingly.
Thank you." (client-provided description)