Ecamm Live streams live video, which means that your internet upload speed needs to be fast enough to send video in real time.
For the default video size (720p), the minimum recommended upload speed is 1 Mbps. For HD quality video, 4 Mbps is required.
For 1080p video streaming, an upload speed of 10Mbps is recommended.
For 4K video streaming, an upload speed of 25Mbps is recommended.
If you're not sure about your upload speed, run an online speed test, for example Ookla's Speedtest.net. When the test is complete, check the value for UPLOAD.