I’ve found Techwash (for cleaning to restore DWR) and TX Direct (to reproof with DWR) work pretty well. With any DWR, if a garment gets particularly contaminated it can prove impossible to reproof because the dirt stops the DWR working (like a seabird in an oil slick).
This happened to my Paramo Velez recently (after over 10 years). The garment then needs much more hardcore washing (beware doing something that will knacker a membrane/coated garment or unstick taped seams) until the contaminants are removed, then clean with Tech Wash to remove any detergent residues and then reproof).
Dirt is the biggest enemy of water repellency, be it on outdoor gear, birds or mammals.