On that page, one of the links is to rseek.org, which is the page that I use and have used for a number of years. It searches various locations of the R list archives and other online resources. Once you run a keyword search, if you select the "Support" tab, it will filter the search results to online documents and the list archives. The list archives will tend to be either from the Nabble site, which mirrors a subset of list archives, or from https://stat.ethz.ch which is the official R list archive server for all R lists.
Depending upon the keyword search, you may find that the list archive hits will be interspersed with other online resources, with a bias towards one or the other based upon the underlying Google algorithms being used.
Also, as an additional pointer, on the main R Project page is a link to "Getting Help", which takes you to:
Just about any question you can imagine for R has been asked usually
several times. Since you don't explain what specifically you are
looking for help with, the best start is to go to the
https://www.r-project.org/help.html page and start with those
suggestions. Nabble is another good choice, and simply entering "r
[topic]" in a search engine will usually yield hundreds of results.
If I understood correctly a recent discussion on another mailing list,
gmane.org web interface is broken, but will work if you use
news.gmane.org using your news reader, if you use one. That won't solve
your search problem, but just saying.