Lost Connection mySQL caused by plugin Actions

Hi everyone,
I had to manage a Piwik installation who have been deployed 2 years ago.
I recently discovered the dashboard doesn’t manage to display any graphics and I have this message:

SQLSTATE[HY000]: General error: 2013 Lost connection to MySQL server during query - caused by plugin Actions

So I decied to investigate a little bit.
Actually there’s no cron task to auto archive archive log. The parameter was still on the default value: Yes ( archive reports when viewing in browser)
The “delete logs task” was disabled so I decided to enable and keep 180 days.
The DB size is 170MB after deleting old logs and I’m using a shared server hosted by OVH (I’m in French)

If I keep the parameter in System -> General -> Archive reports when viewing in browser the dashboard can’t display any graphics.
But if I turn the parameter to “No” (and set to 3600seconds), the dashboard manage to display graphics but every graph is displaying zero visitor. As I had just installed Piwik.
The “Real Time Visitor” widget tell me there is some visitor on my website but I can’t any report.

FYI : I can’t change any mySQL server parameters (cause I’m on a low cost webhosting offer)
I already tried this: Error: 2006 MySQL server has gone away - caused by plugin Actions

Does anyone have an idea or solution? Do you think I’ should install a piwik?

Thanks in advance everyone !