A communications system includes a data network that is coupled to an access system, which enables access to the data network by a client system. The client system issues requests through a router and the access system, with the requests specifying a server system as the destination. The server system sends response messages back to the client system through the data network and the router. The router is capable of modifying an indication of the maximum size of at least a portion of a message. This ensures that response messages communicated by the server system are not too large that the access system is unable to handle the response messages.