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The strange case of Xfinity login failure

📅 2021-Feb-04 ⬩ ✍️ Ashwin Nanjappa ⬩ 🏷️ xfinity ⬩ 📚 Archive

I recently moved and thus had to enable a new Xfinity broadband internet connection at my new place. The connection was enabled and I could access all websites on the web, except for Xfinity’s own customer portal!

Cannot access Xfinity portal using a Xfinity broadband connection!

Shockingly, this seems to be a common problem with Xfinity customers. I tried everything I could think of and was suggested online: restarting the broadband modem, restarting the wireless router and changing the DNS servers. No dice.

By using rudimentary Linux network tools, it was obvious that when connected from inside Xfinity’s network, the DNS/IP/routing they were doing for customers was screwed up:

$ host is an alias for has address has IPv6 address 2001:558:fe16:109:96:114:156:145

$ nslookup
Non-authoritative answer:       canonical name =
Address: 2001:558:fe16:109:96:114:156:145

$ ping
PING ( 56(84) bytes of data.
--- ping statistics ---
13 packets transmitted, 0 received, 100% packet loss, time 12036ms

Notice how host and nslookup returned different IP addresses. And ping used a third different IP address. And none of those IP addresses were pingable.

In the end, I had to use my cellphone’s mobile data connection to access the customer portal of my home broadband internet provider! The portal opened up fine. Going by the complaints online, Xfinity just does not seem to care about this problem. I have been getting by accessing the portal through my cellphone or through a portable hotspot on my computer.

© 2022 Ashwin Nanjappa • All writing under CC BY-SA license • 🐘📧