diff --git a/proxmox/templates/config/buster-preseed.cfg b/proxmox/templates/config/preseed.cfg
rename from proxmox/templates/config/buster-preseed.cfg
rename to proxmox/templates/config/preseed.cfg
diff --git a/proxmox/templates/debian_buster.json b/proxmox/templates/debian_bullseye.json
copy from proxmox/templates/debian_buster.json
copy to proxmox/templates/debian_bullseye.json
--- a/proxmox/templates/debian_buster.json
+++ b/proxmox/templates/debian_bullseye.json
@@ -22,7 +22,7 @@
       "username": "{{ user `username` }}",
       "password": "{{ user `password` }}",
       "node": "{{ user `proxmox_node` }}",
-      "vm_id": 10003,
+      "vm_id": 10005,
       "memory": 1024,
       "sockets": "1",
       "cores": 2,
@@ -45,8 +45,8 @@
       "cloud_init": "true",
       "cloud_init_storage_pool": "proxmox",
 
-      "iso_url": "https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-10.6.0-amd64-netinst.iso",
-      "iso_checksum": "2af8f43d4a7ab852151a7f630ba596572213e17d3579400b5648eba4cc974ed0",
+      "iso_url": "https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-11.0.0-amd64-netinst.iso",
+      "iso_checksum": "ae6d563d2444665316901fe7091059ac34b8f67ba30f9159f7cef7d2fdc5bf8a",
       "iso_storage_pool": "proxmox-cephfs",
       "unmount_iso": "true",
 
@@ -58,7 +58,7 @@
       "boot_command": [
           "<esc><wait>",
           "install <wait>",
-          "preseed/url={{ user `http_server` }}/buster-preseed.cfg <wait>",
+          "preseed/url={{ user `http_server` }}/preseed.cfg <wait>",
           "debian-installer=en_US.UTF-8 <wait>",
           "auto <wait>",
           "locale=en_US.UTF-8 <wait>",
@@ -86,8 +86,8 @@
       "ssh_timeout": "15m",
       "ssh_password": "installer",
 
-      "template_name": "debian-buster-{{ user `template-suffix` }}",
-      "template_description": "debian buster, generated on {{ user `template-date` }}"
+      "template_name": "debian-bullseye-11.0-{{ user `template-suffix` }}",
+      "template_description": "debian bullseye, generated on {{ user `template-date` }}"
     }
   ],
   "provisioners": [
diff --git a/proxmox/templates/debian_buster.json b/proxmox/templates/debian_buster.json
--- a/proxmox/templates/debian_buster.json
+++ b/proxmox/templates/debian_buster.json
@@ -22,7 +22,7 @@
       "username": "{{ user `username` }}",
       "password": "{{ user `password` }}",
       "node": "{{ user `proxmox_node` }}",
-      "vm_id": 10003,
+      "vm_id": 10004,
       "memory": 1024,
       "sockets": "1",
       "cores": 2,
@@ -45,8 +45,8 @@
       "cloud_init": "true",
       "cloud_init_storage_pool": "proxmox",
 
-      "iso_url": "https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-10.6.0-amd64-netinst.iso",
-      "iso_checksum": "2af8f43d4a7ab852151a7f630ba596572213e17d3579400b5648eba4cc974ed0",
+      "iso_url": "https://cdimage.debian.org/cdimage/archive/10.10.0/amd64/iso-cd/debian-10.10.0-amd64-netinst.iso",
+      "iso_checksum": "c433254a7c5b5b9e6a05f9e1379a0bd6ab3323f89b56537b684b6d1bd1f8b6ad",
       "iso_storage_pool": "proxmox-cephfs",
       "unmount_iso": "true",
 
@@ -58,7 +58,7 @@
       "boot_command": [
           "<esc><wait>",
           "install <wait>",
-          "preseed/url={{ user `http_server` }}/buster-preseed.cfg <wait>",
+          "preseed/url={{ user `http_server` }}/preseed.cfg <wait>",
           "debian-installer=en_US.UTF-8 <wait>",
           "auto <wait>",
           "locale=en_US.UTF-8 <wait>",
@@ -86,7 +86,7 @@
       "ssh_timeout": "15m",
       "ssh_password": "installer",
 
-      "template_name": "debian-buster-{{ user `template-suffix` }}",
+      "template_name": "debian-buster-10.10-{{ user `template-suffix` }}",
       "template_description": "debian buster, generated on {{ user `template-date` }}"
     }
   ],
diff --git a/proxmox/templates/scripts/post-install.sh b/proxmox/templates/scripts/post-install.sh
--- a/proxmox/templates/scripts/post-install.sh
+++ b/proxmox/templates/scripts/post-install.sh
@@ -3,15 +3,14 @@
 ####
 # apt configuration
 ####
-cat <<EOF >/etc/apt/sources.list.d/debian.list
-deb http://deb.debian.org/debian buster main
-deb-src http://deb.debian.org/debian buster main
+source /etc/os-release
 
-deb http://deb.debian.org/debian-security/ buster/updates main
-deb-src http://deb.debian.org/debian-security/ buster/updates main
+cat <<EOF >/etc/apt/sources.list.d/debian.list
+deb http://deb.debian.org/debian ${VERSION_CODENAME} main
+deb-src http://deb.debian.org/debian ${VERSION_CODENAME} main
 
-deb http://deb.debian.org/debian buster-updates main
-deb-src http://deb.debian.org/debian buster-updates main
+deb http://deb.debian.org/debian ${VERSION_CODENAME}-updates main
+deb-src http://deb.debian.org/debian ${VERSION_CODENAME}-updates main
 EOF
 
 export DEBIAN_FRONTEND=noninteractive