Raise your hand if you've ever had problems connecting to the WiFi in hotels or other commercial services: the login page doesn't appear, you get an error when you try to visit any page or you don't they can visit some websites.
If it were impossible to connect to a public WiFi, the causes could be attributable to the configuration of the network of others or, more rarely, to a problem on your client device.
Let's try to summarize the problems that most frequently do not allow you to connect to a public WiFi network.
1) Once the WiFi network is selected on your device, the connection does not take place +R, type ncpa.cpl, right-click the wireless network interface, choose Properties, Internet Protocol Version 4 (TCP/IPv4), click Properties again, then choose the options Obtain an IP address automatically and Get address DNS servers automatically.
Similarly, on mobile devices you will need to access the WiFi section and check that you have not set - in the connection properties - a static private IP address. If so, it will need to be removed.See also Internet Connection Problems, How to Detect and Fix Them.
In Windows, however, we suggest typing at the command prompt: ipconfig /releaseipconfig /renew2) Some WiFis do not allow the use of alternative DNS Some public WiFis do not allow connected users to use DNS servers other than those provided via DHCP from the router. In the article How to block the use of alternative DNS servers within the local network we have seen how to do so, however making sure that even if an unauthorized DNS server is set up on the client, all requests are still redirected to the DNS set on the router side.
However, the managers of some WiFis do not correctly configure the blocking of alternative DNS: it is advisable to try to remove, at least temporarily, those that may have been set manually on your devices.
3) Try setting a static private IPSometimes it happens that due to a configuration error, clients are not correctly assigned a private IP address by the DHCP server.
This situation often arises when the structure that makes the WiFi connection available uses multiple WiFi routers, access points or various range extenders but guiltily leaves the DHCP server active on all the devices.
In these situations, conflicts arise on the IP addresses assigned to the clients which often fail to connect or are suddenly disconnected.
The solution is to try setting a static private IP in the connection properties on your device (notebook, convertible, smartphone or tablet).
The IP address you specify must be included in the range of addresses managed by the WiFi router.
We suggest trying to assign yourself an IP address like the following with subnet mask 255.255.255.0:
1st attempt: 192.168.1.201 (gateway: 192.168.1.1)2nd attempt: 192.168.0.201 (gateway: 192.168.0.1)3rd attempt: 10.0.0.201 (gateway: 10.0.0.1)
The concept is to manually assign your device - without therefore querying the DHCP server - an IP address which, probably, belongs to the range managed by the router and which is probably not in use by other devices.
In Windows, we recommend typing ipconfig /all at the command prompt to verify that static IP addresses are being used correctly.
4) The authentication page never appears Most of the public WiFi networks of hotels and other commercial facilities use a captive portal, i.e. a page for user authentication.
Usually, to gain access to WiFi, just enter your data to receive a confirmation code via SMS or email. In some cases, login via Facebook is required.
The authentication page should automatically appear when visiting any website, but sometimes it does not and the browser shows an error referring to the use of an invalid digital certificate or an unrecognized certificate authority.
To remedy the problem and bring up the authentication page set up by the WiFi manager, we suggest trying to connect to a site that uses the simple HTTP protocol and not HTTPS.
To do this, you can type the URL neverssl.com or clients3.google.com into the address bar of your browser. The captive portal should appear immediately.
On Android devices, the presence of the captive portal is usually automatically detected and the authentication page proposed immediately after choosing the WiFi.
5) If the connection to the WiFi takes place but it is not possible to reach any website From a PC, the first step to take is to open the command prompt and type ping 8.8.8.8 or ping 1.1.1.1 (where 8.8.8.8 is Google's DNS server; 1.1.1.1 that of Cloudflare: DNS Server 1.1.1.1: Cloudflare launches the new service that focuses on privacy).
If a response is received while ping www.google.it gives a negative result (Request timed out), it means that the resolution of the domain names does not take place.
To solve the problem, we recommend going to the network interface properties (WiFi section on mobile devices) and manually setting the DNS servers to use (for example: 8.8.8.8 and 8.8.4.4 or 1.1.1.1 and 1.0. 0.1 as primary and secondary, respectively).
6) How to behave if some sites are unreachable The administrators of the public WiFi network may have imposed a series of limitations to prevent certain types of websites from being visited.
To check if there were any restrictions, just use a VPN client, a fundamental tool to preserve the confidentiality of your data when using public or, worse still, open WiFi networks.
Before setting off, therefore, we suggest equipping yourself with a reliable VPN service (Secure VPN services: how to prevent the real public IP from leaking) or setting up a VPN server to connect remotely in your company, office or at home:
- VPN server, how to create it using a NAS- VPN connection in Windows with OpenVPN
If the authentication page should continue to appear several times while browsing the web, with Android devices it is possible to solve it by installing the WiFi Web Login app: it allows you to log in automatically, dispensing the user from having to repeat the procedure (but it is paid, it costs about 3 euros).
Meanwhile, the use of the so-called HTTP injectors which some users try to use in an attempt to overcome the captive portals is also growing: Bypassing the login to a WiFi and skipping the registration: an increasingly widespread practice.