Sophos XG230 new master node comes with newer firmware version

Question

We have a pair of XG230 running in HA active-passive mode. Both device had same firmware version of 15.01.0 MR- . 
 The master node went down and now the slave is running as standalone. 
 We have purchased a new XG230 but it comes with firmware version of 17.0.6 MR-6. 
 Anyone can advance on how I should re insert the new XG230 back into the HA cluster?

LuCar Toni · Answer

Hi, 
 In fact, i think this is not possible at all. 
 Because you need a old revision of the appliance and need to get the old ISO of V15. 
 The End of Life indicates, that you wont get any support from sophos. 
 So highly recommend you to do the upgrade. 
 There are other security aspects to be on the newest firmware as well. 
 Cheers