Erratum: Transactions of the American Mathematical Society, vol. 369 (2017), 3013-3013.

We consider a spherically symmetric (purely magnetic) Yang-Mills field propagating on an ultrastatic spacetime with two asymptotically hyperbolic regions connected by a throat of radius . Static solutions in this model are shown to exhibit an interesting bifurcation pattern in the parameter . We relate this pattern to the Morse index of the static solution with maximal energy. Using a hyperboloidal approach to the initial value problem, we describe the relaxation to the ground state solution for generic initial data and unstable static solutions for initial data of codimension one, two, and three.