ySQL can be installed on just about every major OS:
Important: Please use only supported versions of the MySQL or MariaDB server. As of January 2019, this is MySQL in at least version 5.6 or MariaDB in at least version 5.5.
We have MariaDB 10 now on Synology… I’ll downgrade tomorow…
Why downgrade when it’s a supported version according to your quote…
Instead, fix your database configuration. Until you can:
telnet 192.168.35.35 3307
from either your Mac or from the Vero you can’t access the database.
telnet 192.168.35.35 3307
Trying 192.168.35.35…
Connected to 192.168.35.35.
Escape character is ‘^]’.
X
5.5.5-10.3.7-MariaDB?4#QOw.w4??!??9_Tg*8|*VT%Xmysql_native_passwordConnection closed by foreign host.
Great, that means you can remotely access it Maria. So now it’s down to getting the login sorted.
I have uninstall MariaDB, PhpMyAdmin…
After, i have install a new MariaDB10 clean with root password
telnet -l root 192.168.35.35 3307
Trying 192.168.35.35...
Connected to 192.168.35.35.
Escape character is '^]'.
HHost '192.168.35.10' is not allowed to connect to this MariaDB serverConnection closed by foreign host.
Same issue but now i know i have a clean MariaDB 
Back to where you started, it’s now refusing remote connections. It was accepting them with your last attempt.
bullshit !!! 
End of my help for you. Good luck!
I have create my osmc user and all is like before now
telnet 192.168.35.35 3307
Trying 192.168.35.35...
Connected to 192.168.35.35.
Escape character is '^]'.
X
5.5.5-10.3.7-MariaDB^{<V|0v%R??!??Nn^o2J^xdjhJmysql_native_password
Thanks for your help bmillham
