diff --git a/INITIAL-COMMANDS.md b/INITIAL-COMMANDS.md
index df64aa7e..e033b576 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 "ISRG Root X2";
-      :local CertFileName "ISRG-Root-X2.pem";
-      :local CertFingerprint "69729b8e15a86efc177a57afb7171dfc64add28c2fca8cf1507e34453ccb1470";
+      :local CertCommonName "Root YE";
+      :local CertFileName "Root-YE.pem";
+      :local CertFingerprint "e14ffcad5b0025731006caa43a121a22d8e9700f4fb9cf852f02a708aa5d5666";
 
       :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 f2afeb54..e4d8755c 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 1f03ad2c..6610ac47 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 f7143ddf..0bcd7083 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/ISRG-Root-X2.pem" dst-path="isrg-root-x2.pem";
+    /tool/fetch "https://rsc.eworm.de/main/certs/Root-YE.pem" dst-path="root-ye.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* [ISRG Root X2 ↗️](https://letsencrypt.org/certs/isrg-root-x2.pem)
+> *Let's Encrypt* / *ISRG* [Root YE ↗️](https://letsencrypt.org/certs/gen-y/root-ye.pem)
 
 Then we import the certificate.
 
-    /certificate/import file-name="isrg-root-x2.pem" passphrase="";
+    /certificate/import file-name="root-ye.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 ("*ISRG-Root-X2*")
+fingerprint. Make sure exactly this one certificate ("*Root-YE*")
 is shown.
 
-    /certificate/set name="ISRG-Root-X2" [ find where common-name="ISRG Root X2" ];
-    /certificate/print proplist=name,fingerprint where fingerprint="69729b8e15a86efc177a57afb7171dfc64add28c2fca8cf1507e34453ccb1470";
+    /certificate/set name="Root-YE" [ find where common-name="Root YE" ];
+    /certificate/print proplist=name,fingerprint where fingerprint="e14ffcad5b0025731006caa43a121a22d8e9700f4fb9cf852f02a708aa5d5666";
 
 ![screenshot: check certs](README.d/03-check-certs.avif)
 
diff --git a/certs/Makefile b/certs/Makefile
index 8b516e4d..c9a33798 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/ISRG-Root-X2 \
+	git.eworm.de/Root-YE \
 	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/ISRG-Root-X2 \
+	rsc.eworm.de/Root-YE \
 	upgrade.mikrotik.com/ISRG-Root-X1
 DOMAINS_IPV4 = \
 	1.1.1.1/SSL-com-Root-Certification-Authority-ECC \
diff --git a/global-functions.rsc b/global-functions.rsc
index 30b0ccbc..10a9b5ac 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 $Return ] = 0) do={
           :error true;
@@ -812,15 +812,10 @@
 # check if DNS is resolving
 :set IsDNSResolving do={
   :do {
-    :local I 1;
-    :retry {
-      :set I ($I ^ 1);
-      :resolve ("low-ttl.eworm." . ({ "de"; "net" }->$I));
-    } delay=50ms max=6;
+    :resolve "low-ttl.eworm.de";
   } on-error={
     :return false;
   }
-
   :return true;
 }
 
@@ -1205,12 +1200,10 @@
   }
 
   :onerror Err {
-    /file/remove [ find where name=$DirName ];
+    /file/remove $DirName;
   } do={
-    :if (!($Err ~ "no such item")) do={
-      $LogPrint error $0 ("Removing directory '" . $DirName . "' failed: " . $Err);
-      :return false;
-    }
+    $LogPrint error $0 ("Removing directory '" . $DirName . "' failed: " . $Err);
+    :return false;
   }
   :return true;
 }
@@ -1236,12 +1229,10 @@
   }
 
   :onerror Err {
-    /file/remove [ find where name=$FileName ];
+    /file/remove $FileName;
   } do={
-    :if (!($Err ~ "no such item")) do={
-      $LogPrint error $0 ("Removing file '" . $FileName . "' failed: " . $Err);
-      :return false;
-    }
+    $LogPrint error $0 ("Removing file '" . $FileName . "' failed: " . $Err);
+    :return false;
   }
   :return true;
 }
@@ -1301,8 +1292,7 @@
   :global SymbolForNotification;
   :global ValidateSyntax;
 
-  :if ([ $CertificateAvailable "ISRG Root X2" "fetch" ] = false || \
-       [ $CertificateAvailable "Root YE" "fetch" ] = false) do={
+  :if ([ $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..9531d4ad 100644
--- a/netwatch-dns.rsc
+++ b/netwatch-dns.rsc
@@ -115,15 +115,13 @@
 
     :local Data false;
     :onerror Err {
-      :local I 1;
       :retry {
-        :set I ($I ^ 1);
         :set Data ([ /tool/fetch check-certificate=yes-without-crl output=user \
           http-header-field=({ "accept: application/dns-message" }) \
           url=(($DohServer->"doh-url") . "?dns=" . [ :convert to=base64 ([ :rndstr length=2 ] . \
-          "\01\00" . "\00\01" . "\00\00" . "\00\00" . "\00\00" . "\09doh-check\05eworm" . \
-          ({ "\02de"; "\03net" }->$I) . "\00" . "\00\10" . "\00\01") ]) as-value ]->"data");
-      } delay=500ms max=6;
+          "\01\00" . "\00\01" . "\00\00" . "\00\00" . "\00\00" . "\09doh-check\05eworm\02de\00" . \
+          "\00\10" . "\00\01") ]) as-value ]->"data");
+      } delay=1s max=3;
     } do={
       $LogPrint warning $ScriptName ("Request to DoH server " . ($DohServer->"doh-url") . \
           " failed: " . $Err);