Overview

This article explains how to troubleshoot the SMP (captive) portal login page not opening for Wi-Fi users.

The portal page can fail to open for two different reasons, and they need different fixes:

• The user's device cannot resolve or reach the portal hostname (a DNS or network issue outside the SMP application).
• The SMP web application (Tomcat) is not running on the server.

Work through the steps below in order. The first step tells you which of these two cases applies.

Solution

Step 1: Capture what the user sees

• On an affected device, open the portal and note the exact URL in the browser address bar and the exact error on screen. Take a screenshot.
• Also note whether users who are already logged in can still browse, or only new logins are failing.
• If the browser reports that the server's DNS address could not be found (for example, errors starting with DNS_PROBE_), the portal hostname is not resolving. Go to Step 2.
• If the hostname resolves but the page times out, shows a connection error, or returns an HTTP error, go to Step 3.

Step 2: Check DNS resolution of the portal hostname

• Find the DNS server addresses that Wi-Fi clients are given when they connect (from the BRAS/BNG user session or the DHCP configuration).
• From a machine on the same network, query each of those DNS servers for the portal hostname:
  • nslookup <portal-hostname> <client-dns-server-ip>
• For comparison, query a public resolver for a well-known domain:
  • nslookup google.com 8.8.8.8
• If the client DNS servers return SERVFAIL or REFUSED, or time out, while the public resolver answers, the problem is in the DNS infrastructure and not in the SMP application. Engage the team that manages those DNS servers. Restarting SMP or Tomcat, or changing SMP configuration, will not fix this.
• After the DNS team applies its fix, repeat the nslookup test and then retry a new login from an affected device.

Step 3: Check the SMP web application (Tomcat)

If the portal hostname resolves correctly but the page still does not open, the Tomcat Bootstrap process may not be running on the SMP server. To check and fix this:

• Run the 'jps' command and check whether the 'Bootstrap' process is running.
  • If it is not running, that could be the root cause.
• Start the process by executing:
  • cd /tomcat/apache/bin
  • sh startup.sh
• Run the jps command again to confirm that the Bootstrap process has started.
• Verify that the portal opens now.

Information to include when you need further help

• The screenshot and exact URL from Step 1, with the time and timezone of the failed attempt.
• Whether already logged-in users are affected, or only new logins.
• The nslookup output from Step 2.
• The jps output from Step 3 from each SMP server.
• SMP application logs covering a few minutes before and after the failed attempt.