What exactly did you do with the suspend script and what do you mean by "it didn't work"?
After adding the systemd service file to /storage/.config/system.d you have to adjust it (if you changed the webui port number in hyperhdr) and then use "systemctl enable NAME_OF_THE_SERVICE_FILE" to enable it.
There are two reasons why I didn't include the suspend script in the addon:
First of all the addon system doesn't support multiple systemd units/services per addon so only the main one (service.hyperhdr) would ever get enabled automatically.
Second, the suspend systemd file contains hard-coded port numbers of 8090 which won't work anymore (and could upset any other service running on that port) if you change the port number in the hyperhdr configuration. That's quite a PITA, even if you change it it would get overwritten on every addon upgrade.
Therefore, just use the manual approach, you only have to do it once after installing and it'll survive addon updates as well.
PS: I can't help testing / verifying if the suspend systemd service works as I don't have any LE systems that support suspend/resume here.
so long,
Hias