diff --git a/doc/contributing/source/enhancements.rst b/doc/contributing/source/enhancements.rst
index 7f96c788b..afb6345f1 100644
--- a/doc/contributing/source/enhancements.rst
+++ b/doc/contributing/source/enhancements.rst
@@ -113,8 +113,8 @@ To submit code proposed for |ns3| as one or more commits, use a merge
 request.  The following steps are recommended to smooth the process.
 
 If you are new to public Git repositories, you may want to read
-`this overview of merge requests <https://docs.gitlab.com/ee/user/project/merge_requests/getting_started.html>`_.  If you are familiar with GitHub
-pull requests, the GitLab.com merge requests are very similar.
+`this overview of merge requests <https://docs.gitlab.com/ee/user/project/merge_requests/creating_merge_requests.html>`_.
+If you are familiar with GitHub pull requests, the GitLab.com merge requests are very similar.
 
 In brief, you will want to fork ns-3-dev into your own namespace (i.e.,
 fork the repository into your personal GitLab.com account, via the user
diff --git a/doc/installation/source/windows.rst b/doc/installation/source/windows.rst
index 03500f159..174cbe66d 100644
--- a/doc/installation/source/windows.rst
+++ b/doc/installation/source/windows.rst
@@ -396,9 +396,9 @@ Windows 10 Vagrant
 ******************
 
 .. _VirtualBox: https://www.virtualbox.org/
-.. _Vagrant: https://www.vagrantup.com/
+.. _Vagrant: https://developer.hashicorp.com/vagrant/docs
 .. _virtual machine: https://www.redhat.com/en/topics/virtualization/what-is-a-virtual-machine
-.. _boxes available: https://app.vagrantup.com/boxes/search
+.. _boxes available: https://vagrantcloud.com/boxes/search
 
 As an alternative to manually setting up all dependencies required by ns-3,
 one can use a pre-packaged `virtual machine`_. There are many ways to do that,
diff --git a/doc/tutorial/source/resources.rst b/doc/tutorial/source/resources.rst
index fc4301444..f42c8673b 100644
--- a/doc/tutorial/source/resources.rst
+++ b/doc/tutorial/source/resources.rst
@@ -36,7 +36,7 @@ as its source code management system, but in December 2018, switch to
 using Git.  Although you do not need to know much about Git in order to
 complete this tutorial, we recommend becoming familiar with Git and using it
 to access the source code.  GitLab.com provides resources to get started
-at: https://docs.gitlab.com/ee/gitlab-basics/.
+at: https://docs.gitlab.com/ee/tutorials/.
 
 CMake
 *****
diff --git a/src/internet/model/tcp-bic.h b/src/internet/model/tcp-bic.h
index 87c8b0aa0..4591ca32b 100644
--- a/src/internet/model/tcp-bic.h
+++ b/src/internet/model/tcp-bic.h
@@ -68,7 +68,7 @@ namespace ns3
  * and the current cWnd size).
  *
  * The reference paper for BIC can be found in:
- * http://an.kaist.ac.kr/courses/2006/cs540/reading/bic-tcp.pdf
+ * https://web.archive.org/web/20220930220436/https://an.kaist.ac.kr/courses/2006/cs540/reading/bic-tcp.pdf
  *
  * This model has a number of configurable parameters that are exposed as
  * attributes of the TcpBic TypeId.  This model also exports trace sources,
diff --git a/src/lte/doc/source/lte-references.rst b/src/lte/doc/source/lte-references.rst
index f2b950819..c3b799b04 100644
--- a/src/lte/doc/source/lte-references.rst
+++ b/src/lte/doc/source/lte-references.rst
@@ -134,7 +134,7 @@ References
 
 .. [Bbojovic2014] B. Bojovic, N. Baldo, `"A new Channel and QoS Aware
    Scheduler to enhance the capacity of Voice over LTE systems"
-   <http://www.cttc.es/publication/a-new-channel-and-qos-aware-scheduler-to-enhance-the-capacity-of-voice-over-lte-systems/>`_,
+   <https://ieeexplore.ieee.org/document/6808890>`_,
    in Proceedings of 11th International Multi-Conference on Systems,
    Signals & Devices (SSD’14), Castelldefels, 11-14 February 2014,
    Castelldefels (Spain).
@@ -142,7 +142,7 @@ References
 .. [Baldo2014] N. Baldo, R. Martínez, P. Dini, R. Vilalta, M. Miozzo,
    R. Casellas, R. Muñoz, `"A Testbed for Fixed Mobile Convergence
    Experimentation: ADRENALINE-LENA Integration"
-   <http://www.cttc.es/publication/a-testbed-for-fixed-mobile-convergence-experimentation-adrenaline-lena-integration/>`_,
+   <https://ieeexplore.ieee.org/document/6843180>`_,
    in Proceedings of European Wireless 2014, 14-16 May 2014, Barcelona
    (Spain).
 
diff --git a/src/mobility/helper/ns2-mobility-helper.h b/src/mobility/helper/ns2-mobility-helper.h
index 45d985a78..1e399c2d3 100644
--- a/src/mobility/helper/ns2-mobility-helper.h
+++ b/src/mobility/helper/ns2-mobility-helper.h
@@ -66,7 +66,7 @@ class ConstantVelocityMobilityModel;
  * The following tools are known to support this format:
  *  - BonnMotion http://net.cs.uni-bonn.de/wg/cs/applications/bonnmotion/
  *  - SUMO http://sourceforge.net/apps/mediawiki/sumo/index.php?title=Main_Page
- *  - TraNS http://trans.epfl.ch/
+ *  - TraNS https://web.archive.org/web/20190512111856/http://lca.epfl.ch/projects/trans/
  *
  *  See usage example in examples/mobility/ns2-mobility-trace.cc
  *