Member Avatar for daram

I have been regularly logging on to local library's public wi-fi network with 2 different laptops. After connecting to the network, any attempt to load a Web page brought up the library's portal, which requires users to agree to terms & conditions, upon which normal Web access is granted.

Today one laptop worked as normal but the other failed. Other patrons in the past had approached me for help because they had experienced the same problem. Web pages simply wouldn't load, but the portal log-in never comes up. I copied the login page URL into a browser and that brought up the portal, but upon clicking the "I agree" button, an "invalid username/password" message pops up (in 3 different browsers). The other laptop worked as usual.

I used Fiddler2 to inspect the HTTP request headers on both laptops and they were identical, (including the login and password, which otherwise are invisible). I tried adjusting security/firewall settings, deleting all temp Internet files, cookies, etc., to no avail.

The library will not help with any connection problems (I don't blame them).

Any other suggestions on what to try? Any help will be greatly appreciated by me and others who ask for help in the future!

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This is a short, pragmatic checklist to try before waiting for a router reboot. The behaviour you describe (portal never appearing or the “I agree” step returning an “invalid” response while another laptop works) is commonly caused by the captive‑portal/gateway holding a stale session tied to a MAC or DHCP lease, or by client‑side caching/proxy/VPN issues. Since already inspected HTTP headers with Fiddler, focus next on the IP/session layer and any local overrides.

Do these from an elevated prompt (Windows) or with equivalent commands on macOS/Linux:

ipconfig /release
ipconfig /renew
ipconfig /flushdns
arp -d *
ipconfig /all     <-- copy the Physical Address (MAC) to give to IT if needed

Also try these client fixes: remove the saved Wi‑Fi profile and reconnect (Windows example):

netsh wlan delete profile name="LibrarySSID"

Use a private/incognito browser window. Disable any VPN, proxy or security appliance temporarily. Check the local hosts file (Windows: C:\Windows\System32\drivers\etc\hosts) for entries that could redirect the portal. If you suspect the gateway still thinks your device is logged‑in, temporarily changing the NIC MAC (Device Manager → adapter → Advanced → Network Address) forces a new session (many drivers support this; some don’t).

What to ask the library IT: give them the MAC from ipconfig /all and the exact local time you connected, and request they purge the captive‑portal session for that MAC or restart the gateway/captive‑portal service (this is more surgical than rebooting the whole router). If staff won’t help, two user workarounds are to change your MAC temporarily or wait for the portal session timeout.

Note: ’s ethernet-light issue is unrelated to captive portals. For that, test with a different cable/port, check the NIC driver in Device Manager, and try the laptop with another known‑good network to isolate hardware versus software.

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Member Avatar for fstacy0528

I have a sony vaio-pcg7113L, it is not picking up the internet. when i plug my modem in the ethernet port the light on the plug is not blinking. Which leads me to believe that there is something wrong with the ethernet port. I have Windows Vista home premium and have no clue how to run a diagnosis on it. I had updated the drivers for the network and made sure everything is set up corectly on the conections. I have unpluged the modem and restarted the computer after i pluged the modem back in. Non of this has worked. also under the device manager it tells me that there is nothing wrong with the ethernet port. Can someone help me with doing a diagnosis on this somputer please. Thanks

Member Avatar for daram

I managed to talk to library's IT person, who said it's a known problem--something about the network not recognizing that a user has logged off for some reason. Only way to get back on is to wait for router reboot, which they apparently don't do unless they have to. Sounds strange to me. I would've liked to get better explanation about why that happens.

I have been regularly logging on to local library's public wi-fi network with 2 different laptops. After connecting to the network, any attempt to load a Web page brought up the library's portal, which requires users to agree to terms & conditions, upon which normal Web access is granted.

Today one laptop worked as normal but the other failed. Other patrons in the past had approached me for help because they had experienced the same problem. Web pages simply wouldn't load, but the portal log-in never comes up. I copied the login page URL into a browser and that brought up the portal, but upon clicking the "I agree" button, an "invalid username/password" message pops up (in 3 different browsers). The other laptop worked as usual.

I used Fiddler2 to inspect the HTTP request headers on both laptops and they were identical, (including the login and password, which otherwise are invisible). I tried adjusting security/firewall settings, deleting all temp Internet files, cookies, etc., to no avail.

The library will not help with any connection problems (I don't blame them).

Any other suggestions on what to try? Any help will be greatly appreciated by me and others who ask for help in the future!

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