Forwarding problem?

Hi there

I’ve got a forwarding problem that I can’t seem to fix!

My domain https://www.transenduro.co.uk forwards to https://www.transenduro.co.uk/wp where I have the WordPress installation. It’s in the “wp” folders as I have other domains forwarding to other folders on that hosting.

So, if I type in https://www.transenduro.co.uk it forwards on to the WordPress site as desired, however if someone types in transenduro.co.uk it hangs and gives me the message “Error establishing a database connection”.

I can’t for the life of me figure out how to make it forward on when the www prefix is not used.

Any ideas please?!