I need help removing grain from this render. it will be a video render so no still image. I dont have a lot of knowledge about octane. Its on direct lighting with 400 samples, i know that isnt a lot but based out of previous experience 400 samples shouldnt look like this.

https://imgur.com/a ...

Hello I am stuck with this problem. I don't have a lot of knowledge about this render but I need to fix this. For clarification I want to make this a video render not just a still picture, modeling isn't completely done.
https://imgur.com/a/bDbSJBT Rendering settings are on Directlightning with 400 ...