Hi all. After jacking ns rear up and os front being really low I now can’t lower the front. Keeps saying ext mode. Connect solus up and rear will go up and down but front just won’t do anything! Only fault I get is unable to exhaust but if that was blocked surely back wouldn’t lower? Any help much appreciated. Thanks

First step is to start the car, let it run for a few minutes, leave in park, hand brake off, carry out steering angle sensor reset.
Turn to full left lock, hold two seconds, go to centre / hold / full right lock / hold back to centre / hold - sometimes repeat process, this can reset the system.
After the car has been lifted it sometimes thinks there is an object under the car thus it will lot lower.
Also have a look under the car and check that all the height sensors look ok In a safe manner!
You could temporarily remove the exhaust filter to take that out of the equation
I have had this where lifting the car to full off road height and leaving it for a few minutes, driving the car forwards a few yards, then lowering the car worked for me.

Reset the fault using a diagnostic tool to see what happens.

More thinking, if the rear lowers but not the front it could be that the valve block on the front is not operating or not getting the message to operate?

Exactly that, I can lower the front by undoing line into valve block but as soon as I lower in the car the front sticks and thinks it’s in extended mode. Might whip the valve block off and check for blockages

If the car thinks it's in extended mode when lowering it could well be a dodgy height sensor, that would be the next thing to check and if the car is sticking as it is dropping with the air line disconnected, then an air bag or something else is stopping the car from dropping ?