interrupted sound and delayed control using a transceiver

Hello,

I'm a Radio Amateur and would like to use a transceiver in my local network using a Raspberry 4 B and VH.

The transceiver is a Yaesu FT 991a (https://www.yaesu.com/indexVS.cfm?cmd=DisplayProducts&ProdCatID=102&enc…). Connected directly by USB it works fine.
Info: The transceiver has a built in sound card for Microphone / Speakers.

Also via VH it works more or less. The Windows 10 Notebook (Thinkpad, I7, 40 GB Ram) recognizes the transceiver and the drivers are installed correctly. BUT.....

1) There's a delay of 0,5 - 3 seconds when I start/stop sending. A maximum of 50-100ms would be good....
2) The TX-Audio (the audio which is broadcasted when I send) is choppy (interrupted about 10 times a second which makes my signal unreadable). But not always.....Sometimes it works, sometimes It doesn't. Since I do Satellite communication and digital modes it's unusable that way. The reception is, however, free of interruptions.

Please let me know how to improve that situation.

Best regards from Germany.
Manuel