Hello MarcH, thanks for your answer! I checked now in company, found that the problem relies probably on the HTTP get request, that fails if there is a dot there. I'm attaching the two pcap files that shows no DNS errors (with or without the dot)
wget connectivity-check.ubuntu.com Prepended http:// to 'connectivity-check.ubuntu.com' --2026-05-07 13:06:30-- http://connectivity-check.ubuntu.com/ Resolving connectivity-check.ubuntu.com (connectivity-check.ubuntu.com)... 91.189.91.97, 91.189.91.98, 185.125.190.99, ... Connecting to connectivity-check.ubuntu.com (connectivity-check.ubuntu.com)|91.189.91.97|:80... connected. HTTP request sent, awaiting response... 204 No Content 2026-05-07 13:06:30 (0.00 B/s) - ‘index.html’ saved [0] wget connectivity-check.ubuntu.com. Prepended http:// to 'connectivity-check.ubuntu.com.' --2026-05-07 13:06:34-- http://connectivity-check.ubuntu.com./ Resolving connectivity-check.ubuntu.com. (connectivity-check.ubuntu.com.)... 91.189.91.96, 185.125.190.99, 91.189.91.98, ... Connecting to connectivity-check.ubuntu.com. (connectivity-check.ubuntu.com.)|91.189.91.96|:80... connected. HTTP request sent, awaiting response... 403 Forbidden 2026-05-07 13:06:34 ERROR 403: Forbidden. So, looks like: 1) if we add the "." char the DNS resolution needs only one request, but the http request fails due to (badly) configured proxies 2) if we keep the change without the "." char, the DNS resolution takes some more packets, but the http request is more robust. We might even patch network manager to strip the "." after the dns resolution process if needed, I have to check the code ** Attachment added: "pcaps.zip" https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/2148643/+attachment/5968734/+files/pcaps.zip -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2148643 Title: [SRU] connectivity-check.ubuntu.com URL change? To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/2148643/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
