Splash page to users when F5 load balancers are down?

Hi, you will need an intermediate device to do this when the LTMs are down, however this should hopefully be unlikely if you have them configured as an HA pair. Do you have a particular problem with your F5s going down?

Other than a maintenance page via an iRule (used when all pool members are down) You would need to use F5 GTM/DNS to use an 'address of last resort' in the event the LTM is down. Some DNS providers can offer a solution like this if you don't have GTM. However I would be more concerned why my LTMs are down so often