Comcast Corp. has a problem — the company is losing customers in its most significant business, providing internet access to nearly 30 million American households.

The Philadelphia-based telecom and media conglomerate has reported record losses of broadband subscribers for three straight quarters, more than half a million accounts in total, after pandemic-related federal subsidies for low-income customers ended and telecom companies like T-Mobile US Inc. got much more aggressive offering consumers alternative options.