Or use a stronger primed like mapei Eco prim grip or Ardex p4 then you use a water mix. Just make sure the tiles are solid.
131 primer then fball 300 for me but I do have a thing about 300 at moment had some real shocking screeds so gone back to it after trying few others
If your tiles are fitted over a wooden subfloor and tiles are loose or grout cracked it suggests the subfloor isn't stable enough and it's a matter of time before before further failing occurs. In that case it's a full rip out.
