When you enter the App center menu, you could only find the pre-installed apps. But others like Linkus, Billing, Hotel etc. are missing.
1. Clean the browser cache and login again to check.
2. Check if PBX has Internet access already with you IT.
3. Check if your DNS in PBX is available to parse appcenter.yeastar.com.
4. Use the PING tool in the Troubleshooting menu to ping the domain appcenter.yeastar.com.
5. Check if the PBX firewall has been checked with Drop All option.
If issue persists, please post the following information to our support.
1. The result of the checklist.
2. The system information in the Resource Monitor menu.