diff --git a/extras/quickstart.sh b/extras/quickstart.sh
index f0c793d..cebd4a4 100755
--- a/extras/quickstart.sh
+++ b/extras/quickstart.sh
@@ -69,8 +69,8 @@ check_os() {
     if [ "$os_ver" = "8" ] || [ "$os_ver" = "jessiesid" ]; then
       exiterr "Debian 8 or Ubuntu < 16.04 is not supported."
     fi
-    if [ "$os_ver" = "10" ] && [ ! -e /dev/ppp ]; then
-      exiterr "/dev/ppp is missing. Debian 10 users, see: https://git.io/vpndebian10"
+    if { [ "$os_ver" = "10" ] || [ "$os_ver" = "11" ]; } && [ ! -e /dev/ppp ]; then
+      exiterr "/dev/ppp is missing. Debian 11 or 10 users, see: https://git.io/vpndebian10"
     fi
   fi
 }
diff --git a/extras/vpnupgrade.sh b/extras/vpnupgrade.sh
index 66fa1bf..51a4e19 100755
--- a/extras/vpnupgrade.sh
+++ b/extras/vpnupgrade.sh
@@ -90,6 +90,10 @@ EOF
       ;;
   esac
 
+  if [ "$SWAN_VER" = "3.32" ] && [ "$os_ver" = "11" ]; then
+    exiterr "Libreswan 3.32 is not supported on Debian 11."
+  fi
+
   ipsec_ver=$(/usr/local/sbin/ipsec --version 2>/dev/null)
   if ! printf '%s' "$ipsec_ver" | grep -q "Libreswan"; then
 cat 1>&2 <<'EOF'
diff --git a/extras/vpnupgrade_ubuntu.sh b/extras/vpnupgrade_ubuntu.sh
index f955e5e..dee1078 100755
--- a/extras/vpnupgrade_ubuntu.sh
+++ b/extras/vpnupgrade_ubuntu.sh
@@ -73,6 +73,10 @@ EOF
     ;;
 esac
 
+if [ "$SWAN_VER" = "3.32" ] && [ "$os_ver" = "11" ]; then
+  exiterr "Libreswan 3.32 is not supported on Debian 11."
+fi
+
 ipsec_ver=$(/usr/local/sbin/ipsec --version 2>/dev/null)
 swan_ver_old=$(printf '%s' "$ipsec_ver" | sed -e 's/.*Libreswan U\?//' -e 's/\( (\|\/K\).*//')
 if ! printf '%s' "$ipsec_ver" | grep -q "Libreswan"; then
diff --git a/vpnsetup.sh b/vpnsetup.sh
index a7ad2e9..d13d795 100755
--- a/vpnsetup.sh
+++ b/vpnsetup.sh
@@ -92,8 +92,8 @@ check_os() {
     if [ "$os_ver" = "8" ] || [ "$os_ver" = "jessiesid" ]; then
       exiterr "Debian 8 or Ubuntu < 16.04 is not supported."
     fi
-    if [ "$os_ver" = "10" ] && [ ! -e /dev/ppp ]; then
-      exiterr "/dev/ppp is missing. Debian 10 users, see: https://git.io/vpndebian10"
+    if { [ "$os_ver" = "10" ] || [ "$os_ver" = "11" ]; } && [ ! -e /dev/ppp ]; then
+      exiterr "/dev/ppp is missing. Debian 11 or 10 users, see: https://git.io/vpndebian10"
     fi
   fi
 }
diff --git a/vpnsetup_ubuntu.sh b/vpnsetup_ubuntu.sh
index e46849b..499f19a 100755
--- a/vpnsetup_ubuntu.sh
+++ b/vpnsetup_ubuntu.sh
@@ -71,8 +71,8 @@ os_ver=$(sed 's/\..*//' /etc/debian_version | tr -dc 'A-Za-z0-9')
 if [ "$os_ver" = "8" ] || [ "$os_ver" = "jessiesid" ]; then
   exiterr "Debian 8 or Ubuntu < 16.04 is not supported."
 fi
-if [ "$os_ver" = "10" ] && [ ! -e /dev/ppp ]; then
-  exiterr "/dev/ppp is missing. Debian 10 users, see: https://git.io/vpndebian10"
+if { [ "$os_ver" = "10" ] || [ "$os_ver" = "11" ]; } && [ ! -e /dev/ppp ]; then
+  exiterr "/dev/ppp is missing. Debian 11 or 10 users, see: https://git.io/vpndebian10"
 fi
 
 if [ -f /proc/user_beancounters ]; then