operation modes xdsl modem router 3g4g router wireless router dhcp server client dhcp client list address reservation dhcp relay quality of service atm qos trafc controlip qos port forwarding virtual server port triggering dmz alg upnp dynamic dns dyndns no ip vpn passthrough pptp l2tp ipsec passthrough atmppp protocols atm forum uni3140 ppp over atm rfc 2364 ppp over ethernet rfc2516 ipoa rfc15772225 meripoe rfc 1483 routed bridge r