Help with a WordPress website host change

I have recently moved a website for a church. Their domain name did not change, only the webhost. It is now on a server I lease as a non-managed Linux box. I have about ten WP sites on it running with no problems.

I have moved WP sites before, but never had this problem. I have imported the sql database, changed the config file to represent that change.

I changed DNS, including the A record,

The front page loads okay, including a slider, (the slider however loads very slowly) the links show up on the bottom left hand corner with the correct, but the page errors.

If I try to access the wp-admin page I get an error stating that the ‘insert old database name’ is down, or the config page is wrong.

Any help would be greatly appreciated.
The website is
admin is

Please help!!!
Tab Smith