I am of course perplexed that you’re complaining about being unable to report a bug about Ubuntu because you need an Internet connection, whilst making a report about that, clearly with an Internet connection. Well done! 😀
However, it’s not unreasonable to have no Internet connect on the machine with the problem, and needing to file the issue from another machine, as it appears you have done here.
As such, you can construct a URL using: https://launchpad.net/ ubuntu / +source / (packagename) / +filebug
(assuming you know the package name – which you don’t mention)
This should take you to a form in which you can specify the problem, some detail regarding the ways to reproduce the issue and any pertinent details.