We study a nonlocal Robin–Venttsel’-type problem for the regional fractional p-Laplacian in an extension domain $$\Omega $$
Ω
with boundary a d-set. We prove existence and uniqueness of a strong solution via a semigroup approach. Markovianity and ultracontractivity properties are proved. We then consider the elliptic problem. We prove existence, uniqueness and global boundedness of the weak solution.