Live streaming over cellular signal and/or WiFi isn’t always reliable where signal strength can fluctuate, causing dropped frames or even a failed live stream. This is especially true if you are using a public WiFi signal.
Trying to stream from within a large crowd of people can also cause connections issues. The cellular signal tends to degrade when lots of people are accessing the same network at the same time. This means that even if you appear to have 5 connection bars, the actual signal to your phone may be a fraction of what you need to sustain live streaming bandwidth.
Bandwidth is the key. Many other issues related to the network can also arise so if you are always having issues, you may want to contact your provider.
Another possible issue would be the Live Streaming service you are using where your stream key has expired or you have a setup issue. YouTube and other services are always changing the rules and configurations so make sure you have logged into the service and your setup is up-to-date.
Here are some related links:connection, live streaming