Amazon’s (Nasdaq: AMZN) unit that runs Web servers for other companies had problems Sunday that coincided with outages or slowdowns on several popular websites.

AirBnB says its site was one of those affected. Other services that were slow or unavailable included Instagram and Twitter’s Vine video-sharing application.

“We know many of you are having trouble loading Instagram. We identified the issue and are working to fix it ASAP,” posted Instagram on its Twitter feed, the Wall Street Journal reported.

Online home rental service AirBnB tweeted at 4:32 p.m. ET that it was one of several websites and apps that were temporarily down because Amazon server problems.

Instagram sent a tweet saying it was aware some users were having trouble loading Instagram and that was working on the problem. Vine later sent a similar tweet.

Amazon Web Services provides companies with online storage and computing power. Its website showed several problems resolved on Sunday evening, with minor issues remaining.

Amazon did not immediately respond to a request for comment.

At 7 p.m. ET videos posted to Vine appeared to be working. Instagram and AirBnB were functioning but slow.

The Journal noted that  ”Amazon advertises that its outsourced Web services are more reliable than companies running their own computer servers,” but also pointed out that “Amazon’s main retail earlier this week also was inoperable for a less than an hour for many customers. Amazon didn’t offer an explanation for the outage.”

Amazon did acknowledge a problem later Sunday with its “Elastic Block Store,” and noted Sunday night that service had been restored, the Journal reported.