How to avoid VOIP calls dropping? (VPN/China/OSX 14.6/OpenConnect/ClashPro)

In China currently and need to make important calls back to Europe which I really only know how to do using Google Voice which requires VPN. My stack is OSX 14.6/OpenConnect/ClashPro. I have turned off fallback mode and am using the proxy with the lowest latency. Calls get consistently dropped anywhere between 1-2mins into the conversation. Is there anything I can do about it other than getting interntional calling with my carrier?

Drops for me if I use “fake ip” in the DNS settings. If I use the other option works fine

Sorry. new to this space; instead of ClashPro?

which client? what I see in my settings is a Fake IP Cache to clear; I asume enhanced mode would not use a Fake IP?

No, a Trojan server.

I see, as an ELI5; I understand they establish connection differently than a vpn. Do i still pay for a commerical subscription? Any (most) established providers?

I use merlin clash on asus router.

Not an expert on this either. My subscription contians some Servers running trojan. I used to have issues with voice calls via WhatsApp, when I used Trojan things worked out for me.