Same Issue here with http://de.archive.ubuntu.com  . Additionally,  I also see GPG error for the  Ubuntu Archive Automatic Signing Key. No problems with other mirrors.

apt-get update
Ign http://de.archive.ubuntu.com trusty InRelease
Ign http://de.archive.ubuntu.com trusty-security InRelease
Ign http://de.archive.ubuntu.com trusty-updates InRelease                      
Ign http://de.archive.ubuntu.com trusty-proposed InRelease
Ign http://de.archive.ubuntu.com trusty-backports InRelease
Hit http://de.archive.ubuntu.com trusty Release.gpg
Hit http://de.archive.ubuntu.com trusty-security Release.gpg
Get:1 http://de.archive.ubuntu.com trusty-updates Release.gpg [933 B]
(...)
Get:12 http://de.archive.ubuntu.com trusty-backports/main amd64 Packages [5,536 B]
Get:13 http://de.archive.ubuntu.com trusty-backports/restricted amd64 Packages [28 B]
Get:14 http://de.archive.ubuntu.com trusty-backports/universe amd64 Packages [26.2 kB]
Get:15 http://de.archive.ubuntu.com trusty-backports/multiverse amd64 Packages [1,245 B]
Get:16 http://de.archive.ubuntu.com trusty-backports/main i386 Packages [5,550 B]
Get:17 http://de.archive.ubuntu.com trusty-backports/restricted i386 Packages [28 B]
Get:18 http://de.archive.ubuntu.com trusty-backports/universe i386 Packages [26.3 kB]
Get:19 http://de.archive.ubuntu.com trusty-backports/multiverse i386 Packages [1,249 B]
Get:20 http://de.archive.ubuntu.com trusty-backports/main Translation-en [3,233 B]
Get:21 http://de.archive.ubuntu.com trusty-backports/multiverse Translation-en [776 B]
Get:22 http://de.archive.ubuntu.com trusty-backports/restricted Translation-en [14 B]
Get:23 http://de.archive.ubuntu.com trusty-backports/universe Translation-en [24.3 kB]
Get:24 http://de.archive.ubuntu.com trusty-proposed/main amd64 Packages [148 kB]
Get:25 http://de.archive.ubuntu.com trusty-proposed/restricted amd64 Packages [28 B]
Hit http://de.archive.ubuntu.com trusty-proposed/universe amd64 Packages
Get:26 http://de.archive.ubuntu.com trusty-proposed/multiverse amd64 Packages [1,134 B]
Get:27 http://de.archive.ubuntu.com trusty-proposed/main i386 Packages [145 kB]
Get:28 http://de.archive.ubuntu.com trusty-proposed/restricted i386 Packages [28 B]
Get:29 http://de.archive.ubuntu.com trusty-proposed/multiverse i386 Packages [1,133 B]
Fetched 1,226 kB in 53s (22.9 kB/s)
W: GPG error: http://de.archive.ubuntu.com trusty-proposed Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <email address hidden>
W: Failed to fetch http://de.archive.ubuntu.com/ubuntu/dists/trusty-updates/main/binary-amd64/Packages  Hash Sum mismatch

W: Failed to fetch http://de.archive.ubuntu.com/ubuntu/dists/trusty-updates/main/binary-i386/Packages  Hash Sum mismatch

E: Some index files failed to download. They have been ignored, or old ones used instead.


# VS.: #


(...)
Get:53 http://de2.archive.ubuntu.com trusty-backports/main Translation-en [3,233 B]
Get:54 http://de2.archive.ubuntu.com trusty-backports/multiverse Translation-en [776 B]
Get:55 http://de2.archive.ubuntu.com trusty-backports/restricted Translation-en [14 B]
Get:56 http://de2.archive.ubuntu.com trusty-backports/universe Translation-en [24.3 kB]
(...)
Fetched 22.8 MB in 12s (1,810 kB/s)                                            
Reading package lists... Done


If I remember correctly,  http://de.archive.ubuntu.com  never worked for trusty...