Recording network data is not possible with current version(s) of Radarbox.
Additional Comment:
My average Range is 100nm in diameter. I had run a recording session for 24h on an average business day. This has delivered me a record file with 271MB file size. Based an the fact, that I had a average flight count of 200 airframes per hour, a network recording function with an average flight count of 2000airframes per hour may (and will) generate more or less un-processable file sizes very quick.