When voice chat hangs on RTC connecting, Discord has assigned a voice server but cannot establish the real-time voice connection to it. Text chat keeps working, because it uses a different connection, while voice needs a clear UDP path that is being blocked or dropped somewhere between your device and Discord.
The fix, in order
Change the voice region. In the server settings, under Overview, switch the voice region to a nearby one, since a distant or faulty region can fail to connect.
Turn off Quality of Service high packet priority. In Discord settings, under Voice and Video, disable QoS, since some routers mishandle those packets and drop the voice connection.
Restart Discord and the router. Close Discord fully, restart the router, then reopen Discord and try the voice channel again.
Turn off the VPN. VPNs often block or reroute the UDP traffic voice needs, so disable the VPN and test voice directly.
Check the firewall and antivirus. Make sure Discord is allowed through Windows Firewall, and check that security software is not blocking UDP traffic for Discord.
Try a different network. Joining voice on a mobile hotspot shows whether the home router or internet provider is blocking the voice connection.
Reinstall Discord. If the problem follows one device only, a clean reinstall clears corrupted voice settings and cached connection data.
If it still happens
If RTC connecting happens in every server and on every network, check Discord's service status, since a voice outage affects everyone the same way. If it only happens on one server, the problem is that server's region, and switching regions or waiting for the server owner to change it is the fix.
Common questions
What does RTC connecting mean? RTC stands for real-time communication. It is the stage where Discord tries to open the live voice connection to its voice server, after text and login have already worked.
Why does text chat work but voice does not? Text uses a standard web connection, while voice uses UDP packets on specific ports. A firewall, router, or VPN can block UDP while leaving text untouched.
Is RTC connecting caused by my microphone? No. A microphone problem affects what others hear, not whether the voice connection opens. RTC connecting is a network problem, not a hardware problem.