diff --git a/INITIAL-COMMANDS.md b/INITIAL-COMMANDS.md
index e033b576..df64aa7e 100644
--- a/INITIAL-COMMANDS.md
+++ b/INITIAL-COMMANDS.md
@@ -18,9 +18,9 @@ Run the complete base installation:
 
     {
       :local BaseUrl "https://rsc.eworm.de/main/";
-      :local CertCommonName "Root YE";
-      :local CertFileName "Root-YE.pem";
-      :local CertFingerprint "e14ffcad5b0025731006caa43a121a22d8e9700f4fb9cf852f02a708aa5d5666";
+      :local CertCommonName "ISRG Root X2";
+      :local CertFileName "ISRG-Root-X2.pem";
+      :local CertFingerprint "69729b8e15a86efc177a57afb7171dfc64add28c2fca8cf1507e34453ccb1470";
 
       :local CertSettings [ /certificate/settings/get ];
       :if (!((($CertSettings->"builtin-trust-anchors") = "trusted" || \
diff --git a/README.d/01-download-certs.avif b/README.d/01-download-certs.avif
index e4d8755c..f2afeb54 100644
Binary files a/README.d/01-download-certs.avif and b/README.d/01-download-certs.avif differ
diff --git a/README.d/03-check-certs.avif b/README.d/03-check-certs.avif
index 6610ac47..1f03ad2c 100644
Binary files a/README.d/03-check-certs.avif and b/README.d/03-check-certs.avif differ
diff --git a/README.md b/README.md
index 0bcd7083..f7143ddf 100644
--- a/README.md
+++ b/README.md
@@ -126,18 +126,18 @@ If you intend to download the scripts from a
 different location (for example from github.com) install the corresponding
 certificate chain.
 
-    /tool/fetch "https://rsc.eworm.de/main/certs/Root-YE.pem" dst-path="root-ye.pem";
+    /tool/fetch "https://rsc.eworm.de/main/certs/ISRG-Root-X2.pem" dst-path="isrg-root-x2.pem";
 
 ![screenshot: download certs](README.d/01-download-certs.avif)
 
 > ℹ️ **Info**: Note that the command above does *not* verify server
 > certificate, so if you want to be safe download with your workstations's
 > browser from CA's website and transfer the file to your MikroTik device:
-> *Let's Encrypt* / *ISRG* [Root YE ↗️](https://letsencrypt.org/certs/gen-y/root-ye.pem)
+> *Let's Encrypt* / *ISRG* [ISRG Root X2 ↗️](https://letsencrypt.org/certs/isrg-root-x2.pem)
 
 Then we import the certificate.
 
-    /certificate/import file-name="root-ye.pem" passphrase="";
+    /certificate/import file-name="isrg-root-x2.pem" passphrase="";
 
 Do not worry that the command is not shown - that happens because it contains
 a sensitive property, the passphrase.
@@ -145,11 +145,11 @@ a sensitive property, the passphrase.
 ![screenshot: import certs](README.d/02-import-certs.avif)
 
 For basic verification we rename the certificate and print it by
-fingerprint. Make sure exactly this one certificate ("*Root-YE*")
+fingerprint. Make sure exactly this one certificate ("*ISRG-Root-X2*")
 is shown.
 
-    /certificate/set name="Root-YE" [ find where common-name="Root YE" ];
-    /certificate/print proplist=name,fingerprint where fingerprint="e14ffcad5b0025731006caa43a121a22d8e9700f4fb9cf852f02a708aa5d5666";
+    /certificate/set name="ISRG-Root-X2" [ find where common-name="ISRG Root X2" ];
+    /certificate/print proplist=name,fingerprint where fingerprint="69729b8e15a86efc177a57afb7171dfc64add28c2fca8cf1507e34453ccb1470";
 
 ![screenshot: check certs](README.d/03-check-certs.avif)
 
diff --git a/certs/Makefile b/certs/Makefile
index c9a33798..8b516e4d 100644
--- a/certs/Makefile
+++ b/certs/Makefile
@@ -12,12 +12,12 @@ DOMAINS_DUAL = \
 	cloudflare-dns.com/SSL-com-Root-Certification-Authority-ECC \
 	dns.google/GTS-Root-RX \
 	dns.quad9.net/DigiCert-Global-Root-G3 \
-	git.eworm.de/Root-YE \
+	git.eworm.de/ISRG-Root-X2 \
 	gitlab.com/USERTrust-RSA-Certification-Authority \
 	lists.blocklist.de/GTS-Root-R4 \
 	matrix.org/GTS-Root-R4 \
 	raw.githubusercontent.com/ISRG-Root-X1 \
-	rsc.eworm.de/Root-YE \
+	rsc.eworm.de/ISRG-Root-X2 \
 	upgrade.mikrotik.com/ISRG-Root-X1
 DOMAINS_IPV4 = \
 	1.1.1.1/SSL-com-Root-Certification-Authority-ECC \
diff --git a/check-health.d/state.rsc b/check-health.d/state.rsc
index 0728b45e..9b3a07a7 100644
--- a/check-health.d/state.rsc
+++ b/check-health.d/state.rsc
@@ -3,7 +3,7 @@
 # Copyright (c) 2019-2026 Christian Hesse <mail@eworm.de>
 # https://rsc.eworm.de/COPYING.md
 #
-# requires RouterOS, version=7.19
+# requires RouterOS, version=7.21
 #
 # check for RouterOS health state - state plugin
 # https://rsc.eworm.de/doc/check-health.md
diff --git a/check-health.d/temperature.rsc b/check-health.d/temperature.rsc
index fdce5dcb..36975cfe 100644
--- a/check-health.d/temperature.rsc
+++ b/check-health.d/temperature.rsc
@@ -3,7 +3,7 @@
 # Copyright (c) 2019-2026 Christian Hesse <mail@eworm.de>
 # https://rsc.eworm.de/COPYING.md
 #
-# requires RouterOS, version=7.19
+# requires RouterOS, version=7.21
 #
 # check for RouterOS health state - temperature plugin
 # https://rsc.eworm.de/doc/check-health.md
@@ -30,8 +30,7 @@
   }
 
   :local TempToNum do={
-    :global CharacterReplace;
-    :local T [ :toarray [ $CharacterReplace $1 "." "," ] ];
+    :local T [ :toarray delimiter="." $1 ];
     :return ($T->0 * 10 + $T->1);
   }
 
diff --git a/check-health.d/voltage.rsc b/check-health.d/voltage.rsc
index 67febc2b..380556cc 100644
--- a/check-health.d/voltage.rsc
+++ b/check-health.d/voltage.rsc
@@ -3,7 +3,7 @@
 # Copyright (c) 2019-2026 Christian Hesse <mail@eworm.de>
 # https://rsc.eworm.de/COPYING.md
 #
-# requires RouterOS, version=7.19
+# requires RouterOS, version=7.21
 #
 # check for RouterOS health state - voltage plugin
 # https://rsc.eworm.de/doc/check-health.md
diff --git a/check-health.rsc b/check-health.rsc
index 51438966..2e864f50 100644
--- a/check-health.rsc
+++ b/check-health.rsc
@@ -3,7 +3,7 @@
 # Copyright (c) 2019-2026 Christian Hesse <mail@eworm.de>
 # https://rsc.eworm.de/COPYING.md
 #
-# requires RouterOS, version=7.19
+# requires RouterOS, version=7.21
 #
 # check for RouterOS health state
 # https://rsc.eworm.de/doc/check-health.md
@@ -31,8 +31,7 @@
   :global ValidateSyntax;
 
   :local TempToNum do={
-    :global CharacterReplace;
-    :local T [ :toarray [ $CharacterReplace $1 "." "," ] ];
+    :local T [ :toarray delimiter="." $1 ];
     :return ($T->0 * 10 + $T->1);
   }
 
diff --git a/doc/check-health.md b/doc/check-health.md
index d67a3dde..86c9e4e4 100644
--- a/doc/check-health.md
+++ b/doc/check-health.md
@@ -4,7 +4,7 @@ Notify about health state
 [![GitHub stars](https://img.shields.io/github/stars/eworm-de/routeros-scripts?logo=GitHub&style=flat&color=red)](https://github.com/eworm-de/routeros-scripts/stargazers)
 [![GitHub forks](https://img.shields.io/github/forks/eworm-de/routeros-scripts?logo=GitHub&style=flat&color=green)](https://github.com/eworm-de/routeros-scripts/network)
 [![GitHub watchers](https://img.shields.io/github/watchers/eworm-de/routeros-scripts?logo=GitHub&style=flat&color=blue)](https://github.com/eworm-de/routeros-scripts/watchers)
-[![required RouterOS version](https://img.shields.io/badge/RouterOS-7.19-yellow?style=flat)](https://mikrotik.com/download/changelogs/)
+[![required RouterOS version](https://img.shields.io/badge/RouterOS-7.21-yellow?style=flat)](https://mikrotik.com/download/changelogs/)
 [![Telegram group @routeros_scripts](https://img.shields.io/badge/Telegram-%40routeros__scripts-%2326A5E4?logo=telegram&style=flat)](https://t.me/routeros_scripts)
 [![donate with PayPal](https://img.shields.io/badge/Like_it%3F-Donate!-orange?logo=githubsponsors&logoColor=orange&style=flat)](https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=A4ZXBD6YS2W8J)
 
diff --git a/doc/fw-addr-lists.md b/doc/fw-addr-lists.md
index 5b29af7c..fe1e748c 100644
--- a/doc/fw-addr-lists.md
+++ b/doc/fw-addr-lists.md
@@ -4,7 +4,7 @@ Download, import and update firewall address-lists
 [![GitHub stars](https://img.shields.io/github/stars/eworm-de/routeros-scripts?logo=GitHub&style=flat&color=red)](https://github.com/eworm-de/routeros-scripts/stargazers)
 [![GitHub forks](https://img.shields.io/github/forks/eworm-de/routeros-scripts?logo=GitHub&style=flat&color=green)](https://github.com/eworm-de/routeros-scripts/network)
 [![GitHub watchers](https://img.shields.io/github/watchers/eworm-de/routeros-scripts?logo=GitHub&style=flat&color=blue)](https://github.com/eworm-de/routeros-scripts/watchers)
-[![required RouterOS version](https://img.shields.io/badge/RouterOS-7.19-yellow?style=flat)](https://mikrotik.com/download/changelogs/)
+[![required RouterOS version](https://img.shields.io/badge/RouterOS-7.21-yellow?style=flat)](https://mikrotik.com/download/changelogs/)
 [![Telegram group @routeros_scripts](https://img.shields.io/badge/Telegram-%40routeros__scripts-%2326A5E4?logo=telegram&style=flat)](https://t.me/routeros_scripts)
 [![donate with PayPal](https://img.shields.io/badge/Like_it%3F-Donate!-orange?logo=githubsponsors&logoColor=orange&style=flat)](https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=A4ZXBD6YS2W8J)
 
diff --git a/doc/netwatch-dns.md b/doc/netwatch-dns.md
index c80b819b..3aafd5d6 100644
--- a/doc/netwatch-dns.md
+++ b/doc/netwatch-dns.md
@@ -4,7 +4,7 @@ Manage DNS and DoH servers from netwatch
 [![GitHub stars](https://img.shields.io/github/stars/eworm-de/routeros-scripts?logo=GitHub&style=flat&color=red)](https://github.com/eworm-de/routeros-scripts/stargazers)
 [![GitHub forks](https://img.shields.io/github/forks/eworm-de/routeros-scripts?logo=GitHub&style=flat&color=green)](https://github.com/eworm-de/routeros-scripts/network)
 [![GitHub watchers](https://img.shields.io/github/watchers/eworm-de/routeros-scripts?logo=GitHub&style=flat&color=blue)](https://github.com/eworm-de/routeros-scripts/watchers)
-[![required RouterOS version](https://img.shields.io/badge/RouterOS-7.19-yellow?style=flat)](https://mikrotik.com/download/changelogs/)
+[![required RouterOS version](https://img.shields.io/badge/RouterOS-7.21-yellow?style=flat)](https://mikrotik.com/download/changelogs/)
 [![Telegram group @routeros_scripts](https://img.shields.io/badge/Telegram-%40routeros__scripts-%2326A5E4?logo=telegram&style=flat)](https://t.me/routeros_scripts)
 [![donate with PayPal](https://img.shields.io/badge/Like_it%3F-Donate!-orange?logo=githubsponsors&logoColor=orange&style=flat)](https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=A4ZXBD6YS2W8J)
 
diff --git a/fw-addr-lists.rsc b/fw-addr-lists.rsc
index ac15c652..7fe41588 100644
--- a/fw-addr-lists.rsc
+++ b/fw-addr-lists.rsc
@@ -3,7 +3,7 @@
 # Copyright (c) 2023-2026 Christian Hesse <mail@eworm.de>
 # https://rsc.eworm.de/COPYING.md
 #
-# requires RouterOS, version=7.19
+# requires RouterOS, version=7.21
 #
 # download, import and update firewall address-lists
 # https://rsc.eworm.de/doc/fw-addr-lists.md
@@ -72,11 +72,13 @@
       :local Data false;
       :local TimeOut [ $EitherOr [ :totime ($List->"timeout") ] $FwAddrListTimeOut ];
 
-      :if ([ :len ($List->"cert") ] > 0) do={
-        :set CheckCertificate true;
-        :if ([ $CertificateAvailable ($List->"cert") "fetch" ] = false) do={
-          $LogPrint warning $ScriptName ("Downloading required certificate (" . $FwListName . \
-              " / " . $List->"url" . ") failed, trying anyway.");
+      :foreach Cert in=[ :toarray delimiter=":" ($List->"cert") ] do={
+        :if ([ :len ($Cert) ] > 0) do={
+          :set CheckCertificate true;
+          :if ([ $CertificateAvailable $Cert "fetch" ] = false) do={
+            $LogPrint warning $ScriptName ("Downloading required certificate (" . $FwListName . \
+                " / " . $List->"url" . ") failed, trying anyway.");
+          }
         }
       }
 
diff --git a/global-config.rsc b/global-config.rsc
index 0bb572b5..86187431 100644
--- a/global-config.rsc
+++ b/global-config.rsc
@@ -112,11 +112,11 @@
 :global FwAddrLists {
 #  "allow"={
 #    { url="https://rsc.eworm.de/main/fw-addr-lists.d/allow";
-#      cert="Root YE"; timeout=1w };
+#      cert="ISRG Root X2:Root YE"; timeout=1w };
 #  };
   "block"={
 #    { url="https://rsc.eworm.de/main/fw-addr-lists.d/block";
-#      cert="Root YE" };
+#      cert="ISRG Root X2:Root YE" };
     { url="https://raw.githubusercontent.com/stamparm/ipsum/refs/heads/master/levels/4.txt";
 #     # higher level (decrease the numerical value) for more addresses, and vice versa
       cert="ISRG Root X1" };
@@ -131,7 +131,7 @@
   };
 #  "mikrotik"={
 #    { url="https://rsc.eworm.de/main/fw-addr-lists.d/mikrotik";
-#      cert="Root YE"; timeout=1w };
+#      cert="ISRG Root X2:Root YE"; timeout=1w };
 #  };
 };
 :global FwAddrListTimeOut 1d;
diff --git a/global-functions.rsc b/global-functions.rsc
index cbaba0e3..30b0ccbc 100644
--- a/global-functions.rsc
+++ b/global-functions.rsc
@@ -310,7 +310,7 @@
 
   :for I from=0 to=([ :len $Input ] - 1) do={
     :local Char [ :pick $Input $I ];
-    :if ([ :typeof [ find "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789" $Char ] ] = "nil") do={
+    :if ([ :typeof [ :find "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789" $Char ] ] = "nil") do={
       :do {
         :if ([ :len $Return ] = 0) do={
           :error true;
@@ -1301,7 +1301,8 @@
   :global SymbolForNotification;
   :global ValidateSyntax;
 
-  :if ([ $CertificateAvailable "Root YE" "fetch" ] = false) do={
+  :if ([ $CertificateAvailable "ISRG Root X2" "fetch" ] = false || \
+       [ $CertificateAvailable "Root YE" "fetch" ] = false) do={
     $LogPrint warning $0 ("Downloading certificate failed, trying without.");
   }
 
diff --git a/netwatch-dns.rsc b/netwatch-dns.rsc
index 7c6a7b5b..ac7ce0ac 100644
--- a/netwatch-dns.rsc
+++ b/netwatch-dns.rsc
@@ -3,7 +3,7 @@
 # Copyright (c) 2022-2026 Christian Hesse <mail@eworm.de>
 # https://rsc.eworm.de/COPYING.md
 #
-# requires RouterOS, version=7.19
+# requires RouterOS, version=7.21
 # requires device-mode, fetch
 #
 # monitor and manage dns/doh with netwatch
@@ -17,7 +17,6 @@
   :local ScriptName [ :jobname ];
 
   :global CertificateAvailable;
-  :global CharacterReplace;
   :global EitherOr;
   :global IsDNSResolving;
   :global LogPrint;
@@ -104,7 +103,7 @@
   }
 
   :foreach DohServer in=$DohServers do={
-    :foreach DohCert in=[ :toarray [ $CharacterReplace ($DohServer->"doh-cert") ":" "," ] ] do={
+    :foreach DohCert in=[ :toarray delimiter=":" ($DohServer->"doh-cert") ] do={
       :if ([ :len $DohCert ] > 0) do={
         :if ([ $CertificateAvailable $DohCert "fetch" ] = false || \
              [ $CertificateAvailable $DohCert "dns" ] = false) do={