Any alert that uses suppression techniques needs to be an advanced alert.
Then in the alert rules, for the device alerts you want to suppress, add an AND statement that makes the alert conditional on the up / down status of the other device.
Very simply, if you have devices A, B, and C, where B and C are behind, or dependent on device A, then your alert rule for B or C would look something like:
Generate Alert where B is down and A is up.
This would then suppress down alerts for device B if device A is down.
Just as another note, depending on where you are located, a more efficient way of confirming internet access would be for you to ask your ISP for their gateway address & ping that, or else a web server hosted at least in your town.
Less hops, less time.
Thank you for your answer, actually there is no AND option on the advanced tab that I can not chain the rule.
I made 3 post about this (not proud but there was an error yesterday whend trying to post) the last one have a Image about what im trying to do, il try to put the url here.