Hello @Burak_ER,
welcome to the community of Nextcloud 
You started a topic in support category. Unfortunately you ignored the template and a lot of information to help you is missing. Please edit your original post and add all required details like Nextcloud version, webserver type and version, os version, related log file content. Use the support template.
Without additional information the community members cannot help you.
Regards,
wwe
In general you need stun or turn to allow media connection between different networks. Both require direct internet connectivity - no chance to run behind tunnel/proxy etc..
https://www.metered.ca/tools/openrelay/stun-servers-and-friends