Hands up who has never had any problem in connecting to the hotel WiFi or other commercial services: the login page does not appear, you receive an error when you try to visit any page or you are unable to visit some websites.
If it is 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 are most often do not allow you to connect to a public WiFi network.
Unable to connect to a public WiFi such as that of hotels and businesses!
1) Select the WiFi network on your device, the connection does not take place
If you connect to the public WiFi network from a Windows system and the icon at the bottom right displays the message Limited connection, it is good to press the combination of Windows + R keys, type ncpa.cpl, right click on the wireless network interface, choose Properties, Internet Protocol version 4 (TCP / IPv4), click Properties again then choose the options Obtain IP address automatically and Obtain DNS server address 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.
In Windows, however, we suggest typing, at the command prompt:
ipconfig / release
ipconfig / renew.
2) Some WiFi do not allow the use of alternative DNS
Some public WiFi do not allow connected users to use DNS servers other than those provided via DHCP by router. In the article How to block the use of alternative DNS servers within the local network we have seen how to do this, making sure that even if an unauthorized DNS server is set on the client, all requests are still diverted to the DNS set on the router side.
The managers of some WiFi, however, do not correctly configure the blocking of alternative DNS: it is advisable to try to remove, at least temporarily, those possibly set manually on their devices.
3) Try to set a static private IP
Sometimes it happens instead of a configuration error clients are not correctly assigned a private IP address by the DHCP server.
This situation often occurs when the structure that makes the WiFi connection available uses multiple WiFi routers, access points or different range extenders but guilty leaves the DHCP server active on all devices.
In these situations, conflicts arise on the IP addresses assigned to clients that often cannot connect or are suddenly disconnected.
The solution consists in trying to set a static private IP in the connection property 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 self-assign IP address like the following with sub net 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 to your device — without therefore querying the DHCP server — 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 the correct use of static IP addresses.
4) The authentication page never appears.
Most public WiFi networks of hotels and other commercial structures use a captive portal or a page for user authentication.
Usually, to get 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 this does not happen and the browser shows an error referring to the use of an invalid digital certificate or an unrecognized certification 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 and not HTTPS protocol.
To do this, you can type the URL neverssl.com or clients3.google.com in the browser's address bar. Thus, the captive portal should appear immediately.
On Android devices the presence of the captive portal is usually automatically detected, and the proposed authentication page immediately after choosing the WiFi.
5) If the connection to the WiFi takes place but no website can be reached
From a PC, the first step 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 the Google DNS server; 1.1.1.1 that of Cloudflare: DNS server 1.1.1.1: Cloudflare launch the new service that focuses on privacy).
To solve the problem we recommend going to the properties of the network interface (WiFi section on mobile devices) and manually set the DNS servers to be used (for example: 8.8.8.8 and 8.8.4.4 or 1.1.1.1 and 1.0.0.1 respectively as primary and secondary).
6) What to do if some sites are unreachable
The administrators of the public WiFi network may have imposed a series of limitations to prevent the visit of certain types of websites.
To check if there were any restrictions, just use a VPN client, which is also a fundamental tool to preserve the confidentiality of your data when using public or, even worse, open WiFi networks.
Before setting off, therefore, we suggest that you equip yourself with a reliable VPN service (Secure VPN services: how to prevent the real public IP from spreading out) or set up a VPN server to connect remotely to the company, office or home:
— VPN server, how to create it using a NAS
— VPN connection in Windows with OpenVPN
If the authentication page continues to appear several times while browsing the web with Android devices it is possible to resolve by installing the WiFi Web Login app : it allows you to log in automatically releasing the user from having to repeat the procedure (however, it is paid. It costs about 3 euros).
In the meantime, 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.
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