You have to communicate with people that you need a block of time without interruptions and that you only have a certain amount of the day to dedicate to things that aren't your own work. Your manager has to be on board and enforce this.

Otherwise you need to get another job.

To be fair I do get interruptions from Discord for my website that aren't related to other projects but I usually deliberately prioritize them because it's my business and no one else can provide support for it.