How often are you taking him out? Have you tried crate training? Also, have you tried containing him to a smaller area using something like a xpen with the pad inside? Once he starts to understand that he needs to use the pad, slowly increase his space.
Some pups can be bit more stubborn than others. 4 months is still really young too don't be discouraged. I'm sure many memebers here (including myself) had gone through similar/same situation so we understand your frustration. Just have lots of patients and it'll all work out!
Your Toby's just adorable.
