Digital networking event | Video call with large numbers

I am looking to host a digital networking event with around 500 people on an open-source video calling platform. However, when using Jitsi, I’ve found it begins to fall over with only 30 people in the call, so this is likely not a suitable option.

The platform would need to support break out rooms to allow the networking to take place and provide a space for guest speakers to interact with an audience.

If anybody could offer any advice on how is best to go about hosting a large digital networking event on an open-source platform, that would be greatly appreciated.

Many thanks.