Comparison D-Link DIR-615/T4 vs D-Link DIR-615S

The maximum speed provided by the device when communicating wirelessly in the 2.4 GHz band.

This range is used in most modern Wi-Fi standards (see above) - as one of the available or even the only one. The theoretical maximum for it is 600 Mbit. In reality, Wi-Fi at a frequency of 2.4 GHz is used by a large number of client devices, from which congestion of data transmission channels emerges. Also, the number of antennas affects the speed performance of the equipment. It is possible to achieve the speed declared in the specification only in an ideal situation. In practice, it can be noticeably smaller (often by several times), especially with an abundance of wireless technology simultaneously connected to the equipment. The maximum speed at 2.4 GHz is specified in the characteristics of specific models to understand the real capabilities of Wi-Fi equipment. As for the numbers, according to the capabilities in the 2.4 GHz band, modern equipment is conditionally divided into models with speeds up to 500 Mbit inclusive and over 500 Mbit.

Gain provided by each device antenna; if the design provides for antennas with different characteristics (a typical example is both external and internal antennas), then the information, usually, is indicated by the highest value.

Amplification of the signal in this case is provided by narrowing the radiation pattern — just as in flashlights with adjustable beam width, reducing this width increases the illumination range. The simplest omnidirectional antennas narrow the signal mainly in the vertical plane, "flattening" the coverage area so that it looks like a horizontal disk. In turn, directional antennas (mainly in specialized access points, see "Device type") create a narrow beam that covers a very small area, but provides a very solid gain.

Specifically, the gain describes how powerful the signal is in the main direction of the antenna compared to an perfect antenna that spreads the signal evenly in all directions. Together with the power of the transmitter (see below), this determines the total power of the equipment and, accordingly, the efficiency and range of communication. Actually, to determine the total power, it is enough to add the gain in dBi to the transmitter power in dBm; dBi and dBm in this case can be considered as the same units (decibels).

In general, such data is rarely required by the average user, but it can be useful in some specific situations that specialists have to deal with. Detailed calculation methods for suc...h situations can be found in special sources; here we emphasize that it does not always make sense to pursue a high antenna gain. First, as discussed above, this comes at the cost of narrowing the scope, which can be inconvenient; secondly, too strong a signal is also often undesirable, for more details see "Transmitter power".

The power of the transmitter installed in the equipment when operating in the 2.4 GHz band (see "Frequency Band").

This parameter directly affects the overall power and, accordingly, the communication efficiency. For more on this, see p. "Transmitter power" above, but here we separately emphasize that high power is not always required, and in some cases it is frankly harmful.

Additional features (mostly software) supported by the device. These may include DHCP server, FTP server, Web server, file server, media server (DLNA), print server, torrent client, VPN support, DDNS support, and DMZ support, among others. Here is a more detailed description of these functions:

— DHCP server. A function that simplifies the distribution of IP addresses connected to the router (or other network equipment) to subscriber devices. Assigning an IP address is necessary for correct operation in TCP / IP networks (and this is the entire Internet and the vast majority of modern “locals”). In the presence of DHCP, this process can be carried out completely automatically, which greatly simplifies the life of both users and administrators. However, the administrator can also set additional DHCP options — for example, specify a range of available IP addresses (to prevent errors) or limit the time of using one address. If necessary, you can even manually enter a specific address for each device on the network, without automatically adding new devices — DHCP also simplifies this procedure, as it allows you to carry out all operations o...n the router without delving into the settings of each subscriber device.

— FTP server. A feature that allows you to use a Wi-Fi device to store files and access them via FTP. This protocol is widely used to transfer individual files both in local networks and over the Internet. Actually, one of the main differences between this function and the file server (see below) is, first of all, the ability to work via the Internet without much difficulty. In addition, FTP is a common standard protocol and is supported by almost any PC, while a file server can use specialized standards. So if you plan to organize file storage with the simplest and most convenient access, you should choose a device with this function. At the same time, we note that “simple” does not mean “uncontrolled”: FTP allows you to set a login and password for accessing files, as well as encrypt transmitted data. The files themselves can be stored both on the built-in storage of a network device, and on a drive connected to it, such as a USB flash drive or external HDD.

— Web server. The ability to use the router as a web server — storage that hosts ("hosts") a website. Note that this can be both an Internet site and an internal resource of the local network, strictly for personal or official use. Placing the site on your own equipment allows you to do without the services of hosting providers and maintain maximum control over the data on the site and its technical base. On the other hand, this feature significantly affects the cost of equipment, and in terms of memory and processing power, Wi-Fi devices are often inferior to dedicated servers, even based on conventional PCs and laptops (although in some models the memory can be expanded with an external drive). So in this case, the web server mode should be considered mainly as an additional option for relatively simple tasks that are not associated with high loads.

— File server. The ability to use a Wi-Fi device as a server for storing files. This function differs from the FTP server described above in the data transfer protocols used; in other words, a "file server" in this case is a network file storage based on any protocols other than FTP. A specific set of such protocols and, accordingly, the functionality of a Wi-Fi device should be specified separately; we only note that most often we are talking about accessing files over a local network (FTP is traditionally used for Internet access), and the files themselves can be stored both in the router’s own memory, and on a flash drive or external hard drive.

— Media server (DLNA). The ability to create a media library using an external USB drive and transfer content from it to other devices on your home network via cable or Wi-Fi. The function is most in demand for broadcasting video, audio files and images to smart TVs and set-top boxes. In general, the technology was conceived in order to be able to combine different devices into a single network and easily share content within this network, regardless of the model and manufacturer of individual devices. Many modern smartphones and tablets, smart home ecosystem devices, etc. have DLNA support.

— Print server. The ability of the device to work as a print server — a computer that controls the printer. This feature allows you to turn a regular printer into a network printer: all network users will be able to send print jobs through a print server, while such a server will also provide a number of additional features. So, sent jobs will be stored on it until they are executed or canceled, regardless of whether the computer from which they were sent is turned on; remote control of the print queue, etc. may be provided. And the use of a router (or other similar device) in this role is convenient because the router is usually turned on and available all the time.

— Torrent client. The presence in the device of its own torrent client or other data exchange protocol (HTTP, FTP, etc.). This feature allows you to work with file-sharing networks, which are built on the principle of "everyone's own server": the downloaded information is not on a separate computer on the network, but on the computers of the same users. At the same time, the same file can be opened for download in several places and the torrent client simultaneously downloads different parts of it from different sources - this significantly increases the speed. Using a torrent client on a device is convenient in two ways. Firstly, it allows you to offload the main computers of users - an important advantage, given that the torrent client can consume a lot of resources, especially with an abundance of simultaneous downloads / distributions. Secondly, network equipment tends to stay on at all times, allowing downloads and uploads to continue even when users' PCs and laptops are turned off. However, it should be taken into account that despite the presence of such functionality in devices, the open placement of content in torrent networks can violate copyrights. Therefore, use torrent clients in compliance with legal regulations.

— VPN (Virtual Private Network) support. Initially, VPN is a function that allows you to combine devices that are physically located in different networks into a single virtual network. The connection is via the Internet, but the data is encrypted to prevent unauthorized access to it. However, routers, access points and MESH equipment (see "Device Type") more often use a slightly different format of work: connecting to the Internet through a separate VPN server, so that all external traffic from the network served by the router goes through this server. Such a connection has a number of advantages. Firstly, additional traffic encryption increases the security of work. Secondly, “outside” in such cases, it is not the real IP address of the user that is visible, but the address of the VPN server, and in the settings you can set the address related to almost any country in the world. This also has a positive effect on security, and also makes it possible to bypass regional restrictions on visiting individual sites and accessing services.
Note that the VPN can also be “raised” on individual devices on the network (for example, through tools in some Internet browsers); however, a VPN router allows all network devices to work in this format, regardless of whether they support VPN or not. This is particularly useful on smart TVs (to access certain video services like Netflix) and on PS and Xbox (to bypass region restrictions on certain games). On the other hand, note that setting up such a connection on a router can be quite difficult, the connection speed can noticeably drop when working through a VPN, and enabling and disabling this feature on a router is usually more difficult than on user devices.

— DDNS. The device supports the DDNS function — assigning a permanent domain name to a device with a changing (dynamic) IP address. For network electronics, the IP address is of key importance, it is he who allows the equipment to send data packets to the right device. However, such addresses are sequences of numbers that are poorly remembered by a person. Therefore, domain names appeared — on the Internet these are web addresses (for example, ek.ua or e-katalog.ru), on the local network — the names of individual devices (for example, "Work laptop" or "Sergey's Computer"). Both on the Internet and in local networks, the connection between a domain name and an IP address is responsible for the so-called DNS servers: for each domain in the database of such a server, its own IP is registered. However, for technical reasons, situations often arise when the router has to use a dynamic (changeable) IP; accordingly, in order for information to be constantly available on the same domain name, it is necessary to update the data on the DNS server with each IP change. It is this update that the DDNS function provides.

— DMZ. Initially, DMZ is a function that allows you to create a segment on the local network with free access from the outside. From the rest of the network, this segment (it is called the DMZ — “demilitarized zone”) is separated by a firewall that allows only specially permitted external traffic to pass through. This provides additional protection against external attacks: in such cases, the DMZ suffers first of all, and access to other network resources is much more difficult for an attacker. One of the most popular ways to use this feature is to provide access to Internet services, the servers of which are physically located in the company's public local area network. However, it is worth noting that in some inexpensive routers, DMZ may mean the DMZ-host mode, which does not provide any additional protection and is used for completely different purposes (mainly to translate all ports to another network device). So the specific format of DMZ operation needs to be specified separately, especially if you are purchasing a low-cost category device.