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Public wifi connects okay but no internet

Hi, I'm suffering a total inability to connect to the internet via public wifi. The problem is not confined to one wifi network, I've tried on at least three around the local area. However, I encounter two types of wifi when I'm out and about, and only one of them causes the problem. Allow me to clarify:


Type 1: the establishment (a café, for example) hosts its own wifi and internet connection and makes it available to its customers, either with password protection (like my local Costa Coffee) or without (like my local Starbucks). (Sorry about the brand naming, but it's the easiest way to show what I mean). As far as I can tell, these places are running their own internet connection, and simply making it available by wifi. I have no problem connecting in these places.


Type 2: the establishment hosts the wifi, but the functionality is "…powered by AwesomeCorpZone" or something – in North London the main providers are BTOpenzone and TheCloud. These are the ones that I have problems with.


I don't have any problem connecting to the wifi network itself; it's the internet bit that falls down. The type 2 kind of connection should redirect any web page request that I make to the provider's own page allowing me to log in or sign up. But this never happens. If I point my browser at www.google.com for example the browser just shows with “contacting google.com” in the status bar, and nothing happens.


My iPhone has no such problem; in the local Virgin Active gym, for example, wifi internet is provided for members via The Cloud; it is set up so that the first time that one connects to their wifi it redirects web requests to a Virgin-branded web page where members just need to input their gym membership number to get access. On subsequent visits it remembers you and although it still sends you, initially, to the Virgin-branding page that page simply has a 'continue to internet' button that send you on your way to whatever web page you wanted. (An annoying extra step, but that's corporate brand enforcement for you).


On my phone this works fine. On my Macbook Pro, however, I never get sent to the Virgin page, so I can't enter my membership number. (The workaround is to log in with my phone and then tether the phone to the MBP with USB or bluetooth. But it's a kludge).


So that's the situation. Anybody have any advice on what I can change in my settings to allow the MBP to connect the same way as the iPhone?


Sorry for the long post.

Thanks in advance.

MacBook Pro (15-inch Early 2008), Mac OS X (10.7.4), 2.6 GHz, 4GB RAM, 256 GB SSD

Posted on Jul 17, 2012 9:55 AM

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5 replies

Jun 28, 2017 3:17 PM in response to Rick Lecoat

I noticed after performing a Wireshark examination that the probem is not the WIFI its the negotiation with the WIFI portal. For some reason my Mac which is running Yosemite speaks to Apples portal "captive.g.aaplimg.com" which is IP 17.253.17.204. My Mac then receives a response to close. I experienced this issue at GO train station in Toronto Canada.


This is why your WIFI connection shows connected but no Internet traffic. What I don't understand is why the Mac is communicating with Apple for WIFI portals access which is not related to Apple. In the trace below a Http request is sent closing the connection then it starts again.

User uploaded file

Jun 6, 2017 9:36 PM in response to Rick Lecoat

I would like to know what Mac OS your running? I have this same problem and it is not the WIFI on the Mac. I am running Yosemite and on the same machine workstation running Windows 7 I can get onto the public wifi network. I highly suspect this is a specific hack on the Mac OS to prevent WIFI use. I say that because at one time I was working on a public wifi network connected and able to browse then internet connectivity stoped. I was still connected to WIf my DNS pointed to Google DNS so I then went to another public WIFI spot separate company and it did not work.


Got home connected fine set up a wifi router with no password like a public wifi connected fine with no changes to my Mac.

Jun 7, 2017 6:28 AM in response to macfrombrampton

I would check your System Preferences -> Network -> WiFi interface (on the left) -> Advanced -> DNS settings. Many times when you are connected to a network, but the browser cannot find anything, it is because the DNS servers are not translating the domain name into an IP address.


If you wish to try alternate DNS addresses, you could use the [+] button to try one of these

OpenDNS.org

208.67.222.222

208.67.220.220

.

Google DNS

8.8.8.8

8.8.4.4

Jul 17, 2012 2:39 PM in response to Rick Lecoat

With WiFi always keep in the back of your mind there could be a conflicting WiFi base station on the same or "too close" channel. The resulting interference will make it difficult or impossible to access the Internet. The iPhone's antenna is not as large as your portable, so it could be blissfully un-aware of a second - interfering - station.


I always start by ALT-Clicking the WiFi antenna icon and hover the mouse over any other WiFi networks to see a pop-up of signal strength and channel. Make sure nothing is within +/- 2 channels and strong.


After you rule that out, time to check what your network settings are. Take screen shots of these dialogs:

(Shift-Command-4 to get screen shot crosshairs, drag two opposite corners, result is a PNG file and placed on your desktop with current date & time)

User uploaded file

This is basic NETWORK info, needed for your computer to find its way "out" to the internet. When you connect to WiFi there are two stages. The first establishes a radio connection - that is when you get the an indication of signal strength. The second is for network access information to be given to your computer. These are valid values from my home network. Seeing an invalid DNS (anything that starts 169.) indicates your machine did not get the required network information. And nothing will work.


If you are getting their welcome screen, then I would think you are getting valid information. So its time for the next step.



User uploaded file

DNS is how your machine "finds" stuff on the Internet. "8.8.8.8" is Google's main name server. I manually added that for when I travel. I find a lot of hotel and coffee shop networks are messed up. By using Google's name services, I can usually get things working despite local problems.


Some (annoying) providers block Google's number, so you may have to use a local public DNS. Or even subscribe to a private one.


The last thing is a "gotcha":

User uploaded file

Proxies allow by-passing of all the standard network protocols and methods in favour of a defined "use this" server (a proxy). This page should be be blank, like mine. If you use your laptop on a corporate (or bank) network the company (or bank) may use a Corporate proxy system to enhance security. If so, then you likely have to switch that OFF when trying to use public networks.

Public wifi connects okay but no internet

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