I'm a bit confused, but I'd imagine it has to be a patching error. I was playing last night prior to the patch with no issue.
This afternoon (about five and a half hours of tinkering and downloading ago) the skinned launcher attempted to "check and build" the files for patch without success, hovering at 0% [Attachment 1]. After a short time, the message changes to "unable to connect to the network, please try again later" [Attachment 2].
(If my Patcher version appears incorrect, it is due to the said tinkering, attempting to get the updater working.)
I have also tried (after a Windows Update) deleting everything associated with League of Legends from the computer and beginning from a fresh download, but the problem persisted.
I am on a wired University network, but have disabled the local Windows Firewall and specifically opened the relevant ports (UDP 5000-5200 and TCP 2099 & 5223). The university network required installation of Sophos Antivirus, but this does not appear as an active process in the Task Manager [Attachment 3]. My other protection programs (Spybot S&D and MalwareBytes) were present before, and caused no issue. In addition, the problem persists when both are disabled.
The most relevant lines from the log (the rest of which is attached as both .log and .txt) seem to be:
08/10/2010 18:14 [WARNING] Download failed [TORRENTHELPER_ERROR_INVALIDMETAFILE]
08/10/2010 18:14 [WARNING] Attempt to retrieve metafile[LOL.Patcher/12/LOL.Patcher_12_Incremental.solid]
08/10/2010 18:14 [INFO] [LOL.Patcher] State change [PATCHER_STATE_PREPARE] to [PATCHER_STATE_FAILED]
I also ran Hohums' "netalyzr" app, and had only a handful of "red" results, mostly related to Torrenting, presumably to prevent (or at least inhibit) piracy:
Direct UDP access to remote MSSQL servers (port 1434) is blocked. (This is most likely due to a filtering rule against the Slammer worm.)
The applet was unable to send fragmented UDP traffic.
UDP access to remote DNS servers (port 53) appears to pass through a firewall or proxy.
Direct TCP access to remote BitTorrent servers (port 6881) is blocked.
Files of type .torrent are blocked by the network.
Though it's probably a cliche to add, I'm a huge fan and consumer of Riot, and I'd like to assist in any way I can.
EDIT: I saw mention elsewhere on the forums of Pando Media Booster. I don't know from the context whether having it is good or bad (the grammar and language of the post were a bit suspect), but I do have this installed. When the client was reinstalling, I remember seeing the installer mention activating Pando.
EDIT2: Found a LoL Logfile Analyzer by Matricus, added that log to attachments.