AT&T said yesterday that a software defect is slowing down the wireless connection for more than 1 million customers looking to send data from smartphones like Apple’s iPhone 4.

AT&T and supplier Alcatel-Lucent found a problem with Alcatel equipment that is preventing some subscribers from reaching their peak speed when sending data or surfing the Web.

The issue affects less than 2 percent of AT&T’s wireless customers, or about 1.75 million people. Alcatel-Lucent said it was working to fix the software glitch.

An AT&T spokesman declined to comment on which markets were affected by the network problem.

AT&T has dealt with a number of glitches, including allowing private e-mail addresses of about 140,000 owners of cellular-connected iPads to be publicly released, as well as issues with customers attempting to preorder iPhone 4s.