https://nessy.zendesk.com/hc/en-gb/articles/115000886231-iPad-Troubleshooting
"Please note that if your iPad is older than 4th generation Nessy may not function on this device. Older devices may not be able to run the latest version of the app."
Lightspeed - currently using with a number of primaries. Not the cheapest option even with the discount for a 3-year subscription, but simple to implement and maintain.