hi marybd,

since your setup works well with a wired internet connection, this may be a problem with venue's wifi. 

maybe there are a lot of people trying to use the venue's wifi during your performance. 

to check your speed, you can use speed.measurementlab.net or speedtest.net.  if the upload speed is less than  3 mbps or there is packet loss or retransmissions, maybe the venue will allow you to use a wired connection.  long cat 6 ethernet cables such as 100 foot cables are available.  they could be used to connect your equipment to a router or ethernet switch.  lowes and other stores have them for about $50.

please see the following support articles:

Zoom system requirements: Windows, macOS, Linux – Zoom Support

Using original sound for musicians in a meeting – Zoom Support

Configuring professional audio settings for Zoom Meetings – Zoom Support

thanks,  eliot