Questions about the possible connection were widely dismissed four months ago. But the FBI's investigation remains open, the sources said, and is in the hands of the FBI's counterintelligence team -- the same one looking into Russia's suspected interference in the 2016 election.
The server issue surfaced again this weekend, mentioned in a Breitbart article that, according to a White House official, sparked President Trump's series of tweets accusing investigators of tapping his phone.
The FBI declined to comment. The White House did not respond to a request for comment.
The story -- of a possible connection between computer servers -- is a strange tale because there are no specific allegations of wrongdoing and only vague technical evidence.
Internet data shows that last summer, a computer server owned by Russia-based Alfa Bank repeatedly looked up the contact information for a computer server being used by the Trump Organization -- far more than other companies did, representing 80% of all lookups to the Trump server.
It's unclear if the Trump Organization server itself did anything in return. No one has produced evidence that the servers actually communicated.
But for those who have studied the data, the activity could suggest an intent to communicate by email during a period of time when ties between the Trump Organization and Russia are being closely scrutinized because of Russia's alleged involvement in hacking the emails of the Democratic National Committee and Hillary Clinton campaign chief John Podesta.
This issue intrigued a dozen computer researchers at a recent business conference in Washington, D.C. that pulled together the world's top network operators, the ones who help run the internet. To them, it's a strange coincidence that merits further scrutiny.
Earlier, national security adviser to President Trump Michael Flynn resigned amid allegations of contacts with Russian diplomats prior to Trump's inauguration in January 2017.