diff --git a/data/hostname/kafka1.internal.softwareheritage.org.yaml b/data/hostname/kafka1.internal.softwareheritage.org.yaml
index 081ed398..b384da13 100644
--- a/data/hostname/kafka1.internal.softwareheritage.org.yaml
+++ b/data/hostname/kafka1.internal.softwareheritage.org.yaml
@@ -1,55 +1,55 @@
 ---
 networks:
   bond0:
     type: manual
     order: 10
     extras:
       mtu: "9000"
       bond-miimon: 100
       bond-mode: 802.3ad
       bond-xmit_hash_policy: layer3+4
       bond-slaves: enp94s0f0np0 enp94s0f1np1
       bond-lacp-rate: 1
   vlan440:
     type: private
     order: 20
     address: 192.168.100.201
     netmask: 24
     gateway: 192.168.100.1
     mtu: "9000"
     extras:
       vlan-raw-device: bond0
   vlan1300:
     type: static
     order: 20
     address: 128.93.166.48
     netmask: 26
     gateway: 128.93.166.62
-    mtu: "9000"
+    mtu: "1500"
     extras:
       vlan-raw-device: bond0
 
 # Use direct internet access for DNS
 dns::forwarders: {}
 dns::forwarder_insecure: false
 
 backups::exclude:
   - srv/kafka
 
 swh::apt_config::enable_non_free: true
 packages:
   - intel-microcode
   - vlan
   - ifenslave
 
 swh::apt_config::backported_packages:
   buster:
     - linux-image-amd64
     - linux-headers-amd64
     - libnvpair1linux
     - libuutil1linux
     - libzfs2linux
     - libzpool2linux
     - zfs-dkms
     - zfsutils-linux
     - zfs-zed
diff --git a/data/hostname/kafka2.internal.softwareheritage.org.yaml b/data/hostname/kafka2.internal.softwareheritage.org.yaml
index 2aeca7a0..2a5bf180 100644
--- a/data/hostname/kafka2.internal.softwareheritage.org.yaml
+++ b/data/hostname/kafka2.internal.softwareheritage.org.yaml
@@ -1,55 +1,55 @@
 ---
 networks:
   bond0:
     type: manual
     order: 10
     extras:
       mtu: "9000"
       bond-miimon: 100
       bond-mode: 802.3ad
       bond-xmit_hash_policy: layer3+4
       bond-slaves: enp94s0f0np0 enp94s0f1np1
       bond-lacp-rate: 1
   vlan440:
     type: private
     order: 20
     address: 192.168.100.202
     netmask: 24
     gateway: 192.168.100.1
     mtu: "9000"
     extras:
       vlan-raw-device: bond0
   vlan1300:
     type: static
     order: 20
     address: 128.93.166.49
     netmask: 26
     gateway: 128.93.166.62
-    mtu: "9000"
+    mtu: "1500"
     extras:
       vlan-raw-device: bond0
 
 # Use direct internet access for DNS
 dns::forwarders: {}
 dns::forwarder_insecure: false
 
 backups::exclude:
   - srv/kafka
 
 swh::apt_config::enable_non_free: true
 packages:
   - intel-microcode
   - vlan
   - ifenslave
 
 swh::apt_config::backported_packages:
   buster:
     - linux-image-amd64
     - linux-headers-amd64
     - libnvpair1linux
     - libuutil1linux
     - libzfs2linux
     - libzpool2linux
     - zfs-dkms
     - zfsutils-linux
     - zfs-zed
diff --git a/data/hostname/kafka3.internal.softwareheritage.org.yaml b/data/hostname/kafka3.internal.softwareheritage.org.yaml
index 1aeebb61..e0ac6370 100644
--- a/data/hostname/kafka3.internal.softwareheritage.org.yaml
+++ b/data/hostname/kafka3.internal.softwareheritage.org.yaml
@@ -1,55 +1,55 @@
 ---
 networks:
   bond0:
     type: manual
     order: 10
     extras:
       mtu: "9000"
       bond-miimon: 100
       bond-mode: 802.3ad
       bond-xmit_hash_policy: layer3+4
       bond-slaves: enp94s0f0np0 enp94s0f1np1
       bond-lacp-rate: 1
   vlan440:
     type: private
     order: 20
     address: 192.168.100.203
     netmask: 24
     gateway: 192.168.100.1
     mtu: "9000"
     extras:
       vlan-raw-device: bond0
   vlan1300:
     type: static
     order: 20
     address: 128.93.166.50
     netmask: 26
     gateway: 128.93.166.62
-    mtu: "9000"
+    mtu: "1500"
     extras:
       vlan-raw-device: bond0
 
 # Use direct internet access for DNS
 dns::forwarders: {}
 dns::forwarder_insecure: false
 
 backups::exclude:
   - srv/kafka
 
 swh::apt_config::enable_non_free: true
 packages:
   - intel-microcode
   - vlan
   - ifenslave
 
 swh::apt_config::backported_packages:
   buster:
     - linux-image-amd64
     - linux-headers-amd64
     - libnvpair1linux
     - libuutil1linux
     - libzfs2linux
     - libzpool2linux
     - zfs-dkms
     - zfsutils-linux
     - zfs-zed
diff --git a/data/hostname/kafka4.internal.softwareheritage.org.yaml b/data/hostname/kafka4.internal.softwareheritage.org.yaml
index 4d5d8600..964af482 100644
--- a/data/hostname/kafka4.internal.softwareheritage.org.yaml
+++ b/data/hostname/kafka4.internal.softwareheritage.org.yaml
@@ -1,55 +1,55 @@
 ---
 networks:
   bond0:
     type: manual
     order: 10
     extras:
       mtu: "9000"
       bond-miimon: 100
       bond-mode: 802.3ad
       bond-xmit_hash_policy: layer3+4
       bond-slaves: enp94s0f0np0 enp94s0f1np1
       bond-lacp-rate: 1
   vlan440:
     type: private
     order: 20
     address: 192.168.100.204
     netmask: 24
     gateway: 192.168.100.1
     mtu: "9000"
     extras:
       vlan-raw-device: bond0
   vlan1300:
     type: static
     order: 20
     address: 128.93.166.51
     netmask: 26
     gateway: 128.93.166.62
-    mtu: "9000"
+    mtu: "1500"
     extras:
       vlan-raw-device: bond0
 
 # Use direct internet access for DNS
 dns::forwarders: {}
 dns::forwarder_insecure: false
 
 backups::exclude:
   - srv/kafka
 
 swh::apt_config::enable_non_free: true
 packages:
   - intel-microcode
   - vlan
   - ifenslave
 
 swh::apt_config::backported_packages:
   buster:
     - linux-image-amd64
     - linux-headers-amd64
     - libnvpair1linux
     - libuutil1linux
     - libzfs2linux
     - libzpool2linux
     - zfs-dkms
     - zfsutils-linux
     - zfs-zed