I can’t tell you how to quickly fix it. But I can give contacts to a company that has excellent craftsmen. Here they are https://pomplumbing.ca/leaks-investigation-and-repair-on-all-hydronic-systems/. We had problems with water pressure in our beauty salon. At first we thought that everyone had a problem in our area, but it turned out that it was not. That's why they called in specialists. They seemed to clean out the sewer pipe and everything fell into place. Now we work as before, otherwise we have already started losing clients because of this.