Question: After some automatic updates (or being hacked?) I have many things broken and a huge problem to resolve them since **I can't login as root anymore**.

* ssh admin: login success
* su root: permission denied (probably not the same password)

What I have tried:

* read log: but permission denied
* use 'synopass' and empty password: failed
* use synouser: permission denied
* change password of admin hoping it will update the root password: failed.
* check the root user in /etc/passwd: he is ok (with ash)
* restart all the server: failed

I have no idea what is going on. Any advice?

Answer: 
Your Synology probably upgraded to DSM6, in which security has been hardened...
In DSM6 you can no longer use root for SSH, but you can use any other member account of the administrators group. 
Mind that you now need to sudo when logged in using SSH.

See the DSM6 release notes!
If you're still with DSM Version 5, you might have logged in as admin instead of root. This makes a difference, even though root and admin share the same password.

To solve, do

```
ssh root@synology.local

```

with using the admin password.

This will log you in as root, with root access.