Question about Grundig CMS 5000

Hi everyone, I bought your Grundig CMS 5000 hi-fi system less than a year ago and encountered a problem. The device works with all sources except internet radio. Is this a software or fault? Please help. The network is working properly; the Grundig connects to it without reporting any problems. What's more, it reads the station data and displays its logo, but there's no sound; only a nagging hum can be heard. The FM radio works normally, as do other sources. Has anyone encountered a similar problem and how did you resolve it? Both the set and the router have been reset.