I found this around a PS Home fansite which mentions "Source from PlayStation EU". but I can't find the official source. but anyway heres the detail.
"We wanted to take a moment to inform you of a network maintenance, currently scheduled for Monday, April 21st from 5.30 PM to 11.30 PM BST, 9:50 AM to 3:50 PM Pacific Time (12:50 PM to 6:50 PM Eastern Time). We expect this maintenance to last approximately 6 hours.
If you’ve signed in to the network any time since April 16th you will be able to play games online and access partner apps such as Netflix during this maintenance period. The PlayStation Store, PlayStation Home and Account Management will not be available during this time, and users may receive a maintenance notification when attempting to access these services.
We thank you for your patience and support and apologize for any inconvenience this may..."
Haven't heard anything about maintance today. I have been getting the maintance message for the last two days myself. However, did some additional reading and found my system connected properly after completing a system update.
No maintenance now, and no maintenenance back on Jan. 3, when the OP started this thread.