I'm not sure why your computer cannot connect to the patch server. But if you don't figure it out, there's one thing you can do:
Assuming you had the latest patch, you can download the Manual Patch from the Mabinogi Website, under downloads>client & patches. Scroll down and there's a button that says Manual Patch Download. Download that, once it's done, execute that file and it should patch your client and you should be able to get onto mabi shortly.
I don't think this has to do with HackShield but in case you have a problem where HackShield fails to update in the future, you can go to the Nexon folder>Mabinogi Folder>Hackshield>Update. Then there's an application called autoup, which will update your HackShield manually.
Hope this isn't too confusing. See you around in Mabi ^^