Hi
Am not aware about hostname - but you could search for all the devices in your landscape.
From the OneClick Conosle -> Locater Tab -> Devices -> All Devices -> Select Landscapes to Search
To move them to Maintenance Mode:
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From the Contents pane Results window -> Select All the Devices (use the keys Ctrl and A) -> right click, go to the Attribute Editor -> Expand Maintenance Mode -> Double Click "In Maintenance" -> Uncheck "No Change" -> Click Yes (Do not check mark Set As Default) -> Click on Apply
To remove from Maintenace Mode (Follow the same steps as above) -> Double Click "In Maintenance" -> Uncheck "No Change" -> Click No (Do not check mark Set As Default) -> Click on Apply
Click Close -> then OK to exit Attribute Editor
To Schedule Maintenance Mode on all devices:
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From the OneClick Conosle -> Locater Tab -> Devices -> All Devices -> Select Landscapes to Search -> From the Contents pane Results window -> Select All the Devices (use the keys Ctrl and A) -> Now, right click -> Select Utilities -> Schedule Maintenance