Which feature must be disabled in EIGRP for DMVPN spokes to learn routes to other DMVPN spokes?

By default, EIGRP split-horizon prevents a router from advertising a route back out the same interface it was received on, which on a multipoint GRE hub interface means routes learned from one spoke are never forwarded to other spokes connected on that same interface. Disabling split-horizon on the hub's tunnel interface allows the hub to redistribute spoke prefixes to all DMVPN participants, enabling full spoke-to-spoke route reachability.

The bandwidth percent command controls the maximum share of interface bandwidth EIGRP may consume for routing traffic and has no bearing on which routes are advertised between DMVPN nodes.

Next-hop-self is a BGP feature that forces a router to set itself as the next hop for advertised prefixes; it is not an EIGRP parameter and does not affect DMVPN spoke-to-spoke route propagation.

Hold time governs how long EIGRP waits before declaring a neighbor unreachable after missing hellos and does not influence the advertisement or suppression of routes across DMVPN spoke interfaces.