Hi all, have an issue with 2008 Freelander 2 TD4 HSE that is driving me bonkers!

Start the vehicle and everything powers up as normal, occasionally it remains that was but more often than not the radio, phone, Nav screen drop out and the parking sensor buzzer sounds for about 5 seconds. It’s then reboots itself for about 10 seconds and all drops out again….. the cycle continues, sometimes for 5 mins sometimes for an hour and there doesn’t appear to be a pattern.
changed the battery, diagnostic doesn’t show any fault and it’s driving me nuts!
if anyone had had/heard of similar please do let me know. Love my old Freelander but an hour of 5 seconds of a warning buzzer sounding every 10 seconds and phone dropping out is getting rather dull!
Many thanks