The Speedtest Tracker of Henry Whitaker will do the trick. It’s based on Ookla’s Speedtest Cli from which it records recurrently the results.

It looks like this:

It’s quite easy to install and run into a container of DSM 7.x. First, install the “Container Manager”:

Then, register the image of henrywhitaker3/speedtest-tracker:

Next, create a new container with that image and enable auto-start (here, this container wont’ be exposed via the Web Station)

Finally, in the next tab:

• Map a port of your Synology (Ex.: 7080) onto the port 80 of the container (and/or possibly 443).
• Map a shared folder of your Synology (Ex.: /docker/Ookla) onto the folder /config of the container.

Scrolling down in that tab, add an environment variable “OOKLA_EULA_GDPR” with the value “true”.

If you don’t do it, the container will fail to run (it will stop automatically after one or two minutes) and you will find the following message in the Log of the container:

Once the configuration done, you can run the container. Wait for a few minutes before opening the Speedtest Tracker. Once the container up, you should see this in the Logs of the container:

You can now open the Speedtest Tracker (using http(s)://<your NAS IP>:<port configured>) and configure the scheduler to run a test on a regular basis. For that purpose, go to the “Settings” menu . Here under, the pattern ***** is used to run every minute(as per this site).

The default speedtest server in use does not support such a high pace.. It will soon stop and you will see these messages in the Logs:

The follow-up schedule can be use to run every 10 minutes: */10 * * * *

You can possibly look for other speedtest, using this URL : https://www.speedtest.net/api/js/servers?engine=js&https_functional=true&limit=100&search=YOURLOCATION

Use the ID of a server found via that URL in the Settings of the Speedtest Checker…

There are much more settings and other options to configure the container, but this minimal setup runs fine… And you will soon see if your internet connection is stable or not:

Et voilà.