MPTCP connections and their corresponding TCP subfiows are routed by a load balancer toward backends. Each MPTCP connection is routed to a single backend and is able to include primary and secondary TCP subfiows. Routing includes performing, responsive to setting up a primary TCP subflow of an MPTCP connection, load balancing of the connection to select a backend for the connection. The MPTCP connections and their TCP subflows are tracked by the load balancer to route the MPTCP connections and their corresponding TCP subfiows to corresponding selected backends. A backend determines whether a request by a client to set up a primary TCP subflow of an MPTCP connection already includes a key used to generate a token used to uniquely identify the MPTCP connection from other MPTCP connections. The backend generates the token based on the key. The backend uses the token to distinguish subsequent communications for the MPTCP connection.