Slack slash command to discourse in aws ec2


I installed a discourse on aws ec2.
I installed it using a docker. And we are operating well without any problems.

Recently, we are testing the discourse-chat-integration plugin.
Posting from discourse to slack is well connected without issues.
However, the slack slash command does not work normally.

It seems to be a firewall issue of aws. If all security policy is open, slash command works normally but policy can not open all.

I wonder if there is another way.