The question on buses from Shannon Airport to Ennis has been asked several times recently.
The answer has traditionally been buses 51 and 343.
Bus 51 (to Galway) is still correct.
However as from 25 August 2024 the 343 is now Shannon Airport to Limerick only- and is now a 24 hour service- every 20 minutes y day, every hour by night.
To Ennis is now a new service 330- which is Shannon to Ennis only (ie not from Limerick). The timetable has been enhanced to be basically hourly from 0555 to 0005 7 days a week from the Airport, 0500 to 2330 from Ennis.