As far as I've seen, Ruffle never even makes the call out to the server... so at this point I don't think it's a serialization issue although some of what's in that list could potentially cause problems. The Ruffle compatability docs still say that NetConnection has 90% coverage... except for the .connect() call itself, which kinda makes me wonder why bother covering it at all?
That documentation, for stubs, can be somewhat misleading. It just looks for the presence of an avm2_stub_method function call anywhere in the method, which may mean a method that's entirely a stub, or as is the case for NetConnection.connect, a method that is stubbed under specific conditions. NetConnection.connect is stubbed for specifically non-null, non-http commands (generally this is RMTP/RTMFP). See https://github.com/ruffle-rs/ruffle/blob/df11c2206bc6be0a329...