For all of its details of Russia’s hacking, the report is unlikely to settle the questions that linger around the dossier more than two years after it became public. But for those who believe the president’s loyalties are with Moscow, the report’s suggestions of a link between Mr. Gubarev and Russian hacking is likely to spur new demands for renewed investigations, even as Robert S. Mueller III, the special counsel, appears to be wrapping up his investigation.

The dossier is made up of a series of reports compiled in the summer and fall of 2016 by Christopher Steele, a former British spy who runs a firm that conducts investigations for businesses and other clients. The work was done at the behest of President Trump’s political rivals, a fact that Mr. Trump and his allies have seized on in an effort to undermine the Russia inquiry by falsely claiming that it began because of the dossier.

Parts of the dossier have proved prescient. Its main assertion — that the Russian government was working to get Mr. Trump elected — was hardly an established fact when it was first laid out by Mr. Steele in June 2016. But it has since been backed up by the United States’ own intelligence agencies — and Mr. Mueller’s investigation. The dossier’s talk of Russian efforts to cultivate some people in Mr. Trump’s orbit was similarly unknown when first detailed in one of Mr. Steele’s reports, but it has proved broadly accurate as well.

Other parts of the dossier remain unsubstantiated, or nearly impossible to verify, such as its most salacious charge: that the Russians have a video of Mr. Trump cavorting with prostitutes in a Moscow hotel in 2013. At least one accusation — that Michael D. Cohen, Mr. Trump’s former personal lawyer and fixer, met in 2016 with Russian officials in Prague — now looks false after Mr. Cohen, who has turned sharply against Mr. Trump, denied last month during congressional testimony ever visiting Prague.

The report commissioned by BuzzFeed to investigate the dossier did not set out to prove any of those accusations. It was done by FTI Consulting, a Washington-based firm, and focused solely on the accusations against Mr. Gubarev. It relied largely on analyzing internet traffic and other clues, and on digging through public records to glean insight into Mr. Gubarev’s holding company, XBT, and its many affiliates, including Webzilla. Both XBT and Webzilla were named in the dossier as being used for the hacking.

While the report found no direct evidence of a direct link to the Russian hackers, it did conclude that Mr. Gubarev’s web-hosting services are rife with lawlessness. His clients routinely pirate copyrighted material and spread malware, the report found, and his executives appear unconcerned with stopping them or helping authorities track them down.