All routers incorporate a port called WAN (Wide Area Network), and, although these acronyms mean "Wide Area Network", when we talk about WAN we refer to the port through which our router obtains the services of our ISP (Internet operator) , that is, the WAN port is the port through which we connect to the Internet.Do you want to know what its main characteristics are and how to know which is the WAN port of our router?In the old ADSL2+ and VDSL2 routers, the WAN port is the RJ-11 port where we connect the telephone cable.Internally, the router incorporates an ADSL2+ or VDSL2 modem that is responsible for modulating and demodulating the signal to transfer data, and the firmware is responsible for using different connection protocols to the operator's network, such as DHCP or PPPoE among others, both if our ISP provides us the connection with IPv4 or IPv6.The speed of this WAN port will depend on the technology used (ADSL2+ or VDSL2) and the synchronization speed.The appearance of the WAN port in an ADSL2+ or VDSL2 router is the gray one that says “ADSL”.In this case we have a port for the Internet WAN, which is the ADSL connection itself, and four LAN ports to connect the different PCs via cable.In addition, the router is in charge of doing NAT against this WAN port, in this way, all the computers connected to the LAN (home local network) will go to the Internet through the same public IP, something completely normal nowadays until the arrival of the IPv6 protocol.ADSL2+ routers generally incorporate Fast-Ethernet ports, that is, 10/100Mbps speed, however, if we buy a high-end ADSL2+ router, then you will be able to get Gigabit Ethernet speeds without problems, since these routers incorporate this functionality.Operators that provide fiber optic connections to the home (FTTH), currently usually provide routers with integrated ONT, this means that we will only have a single piece of equipment in our home, which will provide connection to all devices.In this case, the Internet WAN port is the PON port, where we must connect the typical yellow cable with an SC connector, which goes from the PTRO (optical PTR) to the PON port of the router.In some routers of the operators, this port is hidden in the back and perfectly protected, in other cases, it is directly in the back as if it were another port.The speed of GPON technology is 2.5Gbps download and 1.25Gbps upload, but normally the media converter that we have in routers with integrated ONT is Gigabit, that is, we will have a maximum of 1Gbps download and 1Gbps upload .The main operators in Spain have already announced that the new routers for their FTTH will incorporate a Multigigabit 2.5G port, so as not to have a bottleneck facing the Internet WAN network, therefore, we will be able to use both GPON technology, as well as be prepared for the XG-PON technology currently used by operators within their network.If our FTTH router does not have a WAN port with Multigigabit technology, we will never get more than approximately 940Mbps (1Gbps contracted), in this way, with the 2.5G Multigigabit port we can get real 1Gbps without any problem.We must bear in mind that we will always lose bandwidth due to header issues, for this reason, customers who have contracted 1Gbps, will really get a maximum of 940Mbps, because the port's own Gigabit Ethernet interface does not give more than itself WAN.In the near future, operators will market Multigigabit routers, both in the WAN and in the LAN, to maximize the speed of fiber optics with a single piece of equipment.If we only have one Multigigabit port on the WAN, we will need to use at least two LAN ports simultaneously to be able to make the most of it.In this case, the router itself is also in charge of doing NAT against this WAN port, regardless of whether it uses DHCP or PPPoE when using IPv4, or if the operator uses IPv6, we will have native IPv6, DS-Lite or similar configurations to provide the service. .In most cases, fiber routers have Gigabit Ethernet ports for the LAN, in this way, we will not have a bottleneck in the wired network, today there are no equipment with a fiber connector and Fast-Ethernet ports, yes it is true that in the first years with FTTH Movistar launched ONT with Fast-Ethernet port.Operators such as Movistar/O2, Vodafone and MasMovil make use of IPv4 networks facing the Internet, some use CG-NAT and others directly public IP addressing.However, the Orange Group in some of its networks does use the IPv6 protocol in DS-Lite configuration, therefore, we will have an IPv4 with CG-NAT to go out to the Internet with this protocol, and later we will have a public IPv6 address for both the router as for the devices that we connect to it.In the case of neutral routers, the WAN Internet port is an RJ-45 port like that of the LAN ports, but normally this port is "painted" in another color, to perfectly differentiate the Internet port from the different ports of the LAN.For example, in the ASUS ROG Rapture GT-AX11000 router, the Internet WAN port is blue, this is where we must connect the typical network cable from the ONT of our operator, the cable-modem, or the xDSL modem that we have, depending on the technology our ISP is using to provide us Internet service.In this case, the speed of the port is governed by the BASE-T standards, therefore, we will commonly have speeds of 10/100/1000Mbps, although we could have higher speeds such as 2.5G, 5G and even 10Gbps if our router allows it.In the case of the ASUS GT-AX11000 router, we have a dedicated Gigabit Ethernet port for the Internet WAN, but it also has a 2.5G port that can function as a LAN port or as an Internet WAN port, therefore, with this router we can have connections of up to 2.5Gbps without problems.Today the top-of-the-range routers from the main manufacturers such as ASUS, NETGEAR or TP-Link, already incorporate Multigigabit ports for the WAN/LAN, in this way, depending on the needs of the user, we can configure this ultra-fast port as a WAN of Internet or as LAN.It is only recommended to configure it as Internet WAN if the operator's ONT or the operator's FTTH router also has Multigigabit ports, otherwise, we will not make the most of this connectivity, and it is more worth configuring it as LAN to connect NAS servers.At RedesZone we have tested other routers with Multigigabit ports such as the ASUS RT-AX86U and ASUS RT-AX89X, the latter with a 10G Multigigabit port and SFP+ port, making it one of the fastest we can currently buy.In addition, these 10G ports can be configured as Internet WAN, with the aim of not having a bottleneck in the wired network.If you are lucky enough to have an Internet connection of more than 1Gbps, you will have to use these ports to get the maximum speed possible and not have any type of limitation.The firmware of the router will allow us to configure the Internet connection, either using the IPv4 or IPv6 protocol, and once the network protocol has been chosen, we will be able to choose if we obtain IP through DHCP, PPPoE or by other methods.A very important detail when buying a neutral router is whether it is compatible with VLANs in the Internet WAN.Currently all FTTH operators in Spain use the 802.1Q protocol to provide Internet connectivity, if the router firmware does not have this, we will not be able to use the router directly.There are operators in Spain that currently provide their clients with an ONT and the router separately, especially the Masmóvil Group when it is working on NEBA (Movistar's network).In this case, the fiber input to the ONT would not be considered an Internet WAN because it does not have the public IP, since the router placed behind it is the one with this public IP.Also, in this specific example case, the Gigabit Ethernet WAN port is from the router itself.In these cases, we must configure any router (that of the operator or one purchased by us) with the corresponding VLAN ID to access the Internet.Therefore, the WAN port of a router is where the Internet connection is, and the port that manages the public IP or the CG-NAT IP, if your operator uses this technology.It is very important to differentiate it from the LAN so as not to make mistakes when connecting the different cables. Also, if you have the ONT and the router separately, you should know that what really is the WAN is the port that has the public IP , the ONT will only be in charge of connecting with the OLT, not of establishing communication at the network level.There are domestic routers, and also routers aimed at a professional public, which not only have a WAN Internet port, but also have a total of 2 WAN Internet ports.These routers allow us to have a double WAN with the aim of providing Internet at all times to the LAN, the firmware of these equipment allows us to have two different configurations.This mode of operation allows the router to take advantage of two Internet connections simultaneously.When we have several clients connected, whether they are wired or wireless, we will be able to “take them out” to the Internet through a WAN connection or another.In this way, if we have two 600Mbps Internet connections on the router, some PCs will go out on one Internet connection and other PCs will go out on the other, with the goal of having a combined speed of about 1,200Mbps.A very important detail is that the speeds are not "added" at any time, but each PC and even each connection that we make, will go through one WAN or another, but not both at the same time "adding" the speeds.If you have two Internet connections that have the same or very similar speed, you can use load balancing to get the most out of both Internet connections.Also, some routers allow you to prioritize one WAN over another, so that one of the two has a higher priority.Let's imagine that we have two Internet connections, one of 600Mbps and the other of 200Mbps, the first is three times as fast as the second, because in the firmware we can make this fast WAN receive three times the traffic from the different PCs, to dimension everything correctly.In this mode of operation, one of the Internet connections will be the primary one, and the other will be the secondary one.In this way, the fastest Internet connection will be the one that carries all the Internet traffic from the computers on the LAN, and the secondary connection will take care of everything in the event that the primary Internet connection goes down.In this way, we will always have availability in our network.If in our house or company we have two Internet connections that have very different speeds, for example, 600Mbps Internet and another that is a 20Mbps ADSL.Our recommendation is that you use this “failover” connection mode, because everything will work better for you using the main WAN, and you will only use the secondary one in the event that the first goes down.Today most ASUS home routers have this Dual WAN function.Likewise, other models such as those from Synology or QNAP also have this feature, so it is not necessary for us to go to professional models to enjoy these functions.