Before jumping into fixes, it helps to know why this happens. According to User Insights , the "0 bytes" indicator is not always a network failure.
The most common cause is that Steam has downloaded data, but your hard drive (HDD) or SSD is too busy writing those files. The network pauses to allow the disk to catch up, resulting in a temporary 0 MB/s network speed. steam download network 0
If the server you are connected to is crowded, changing it can fix the issue. Go to . Before jumping into fixes, it helps to know why this happens