We try to install nextcloud for our customer on hosting servers (LAMP with cPanel onboard). Servers is deploy on datacenter.
There is any issue on talk for customer that connect to server from office where is installed firewall. Seem issue is on VOIP port that a lot of telco closed.
Considering that other video solutions, as hangout or zoom work fine maybe there are further configurations to do.
Here more details about issue:
We search freelance that can setting nextcloud and talk for working fine on Lamp cPanel server where any hosting account can use it.