'‘Domminust’'@'31.170.160.86'
Domminust = login
@ = separator
31.170.160.86 = IP where account is connecting to MySQL server FROM
Check in your registration web function config and in MySQL account manager:
Login (does it exist?)
Password (is it set correctly?)
IP
If your password is correct I would advice you to take a look especially at IP. When you create MySQL account, you can set if your account will be free to use from any connecting IP (you enter % as value) or if it will be bound to one IP, meaning that your account won't be accesible from any other IP address (you enter IP address).