Can not solve drop connection

I have been struggling for more than a month with dropped connections. They keep on sayin it is Openserve although Openserve came to my house and changed the ONT which was not faulty just to show them everything is new and checked the line which was perfect. They keep on blaming Openserve because they can't or don't know how to fix the issue.

I will not recommend them to anyone. And will cancel my subscription and my friends and family which is with them too.