Hi,
This is an official representative of Viber Media.
It could be that the network you are connected to is blocking Viber's traffic.
1. First, please try uninstalling and reinstalling Viber when connecting to a few different WiFi networks (in order to pinpoint the source of the problem). What are the results?
2. Also, please make sure the following ports are enabled ("forwarded") on your routers or firewalls:
TCP: 5242 + 4244
UDP: 5243 + 9785
(if you are not sure how to enable ports, you may contact your router manufacturer)
For more questions or technical support, please visit our official HelpDesk.
Thanks,
Viber