Signal to Noise Ratio Errors The signal-to-noise ratio is the signal to noise. I do not see how a software product would create noise on the line. It's possible because there is less data going over the wire when backups are not running that the SNR noise issues on the line are not noticed. And when backups run and start using more upstream bandwidth, the existing noise is more noticeable since the data is affected and the errors are trying to correct.
Is this multiple customers or just one? I would think an investigation of the broadband connection and the local network is in order. You may be able to measure the SNR from the broadband equipment already connected from Spectrum or your network equipment at the customer.
Please post any updates on this issue as I'd like to track.