You should check your internet connection, and restart your network equipment if necessary. If that doesn’t help, please contact your network administrator or ISP for further assistance. You can find the necessary bandwidth speed information below:

Video chat bandwidth requirements
1:1 call: 650 Kbps up and down
HD mode: 1400 Kbps up and down
3–4 people: 450 Kbps up and (N-1)*400 Kbps down
5–16 people: 184 Kbps up and (N-1)*134 Kbps down
Up and down bandwidth adapts lower based on network conditions

Screen sharing bandwidth requirements
1.2 Mbps up (when presenting) and down (when viewing) for high quality. This adapts as low as 320 kbps based on network conditions.