diff --git a/xCAT-server/lib/perl/xCAT/Postage.pm b/xCAT-server/lib/perl/xCAT/Postage.pm
index 3e009b684..5fda1acfd 100644
--- a/xCAT-server/lib/perl/xCAT/Postage.pm
+++ b/xCAT-server/lib/perl/xCAT/Postage.pm
@@ -177,19 +177,15 @@ my $mn;
 
 =head3 defer_syncfiles_to_postboot
 
-    On Ubuntu/Debian the DISKFUL install runs a node's postscripts inside the installer's
-    in-target chroot -- before the node has booted as itself. The syncfiles postscript works
-    by asking the management node to scp files INTO the running node, which cannot happen in
-    that phase: the not-yet-booted node has no sshd for the MN to reach, so the push times
-    out, syncfiles exits 1, and the node reports status=failed even though the OS installed
-    perfectly. Defer it to the postbootscripts, which run on the booted node where ssh is
-    already listening and the MN's push succeeds.
+    On the Ubuntu/Debian diskful install path a node's postscripts run inside the installer's
+    in-target chroot, before the node has booted as itself. syncfiles asks the management node
+    to scp files INTO the running node, which cannot work there -- there is no sshd yet -- so it
+    times out and the node reports status=failed although the OS installed. Defer it to the
+    postbootscripts, which run on the booted node.
 
-    Scoped to the diskful install path only: netboot and statelite already run their
-    postscripts on the booted node, so moving syncfiles there would change behaviour that
-    works. EL/SLES are unaffected either way -- their postscripts run on the booted node.
-    syncfiles is PREPENDED so it still runs before any postbootscript that consumes the
-    files it synchronises.
+    Scoped to the diskful install path: netboot and statelite already run their postscripts on
+    the booted node, and EL/SLES are unaffected either way. syncfiles is prepended so it still
+    runs before any postbootscript that consumes the files it synchronises.
 
     Arguments:
         $os              nodetype.os for the node
diff --git a/xCAT-server/lib/perl/xCAT/Template.pm b/xCAT-server/lib/perl/xCAT/Template.pm
index a1f71aafd..920a99448 100644
--- a/xCAT-server/lib/perl/xCAT/Template.pm
+++ b/xCAT-server/lib/perl/xCAT/Template.pm
@@ -1686,17 +1686,11 @@ sub ubuntu_subiquity_apt_config
             '      primary:',
             "      - uri: $online_mirror",
         );
-        # On a classic-sources release (20.04/22.04) Subiquity renders the target's
-        # /etc/apt/sources.list from the install media alone (deb file:///cdrom), which lacks
-        # packages xCAT needs such as chrony -- curtin's in-target apt then fails with
-        # "E: Unable to locate package chrony". `sources_list:` is a curtin key that
-        # Subiquity's autoinstall schema ignores, so add the online archive through `sources:`,
-        # which Subiquity honours by writing /etc/apt/sources.list.d/*.list. $RELEASE is
-        # substituted with the release codename by curtin.
-        #
-        # Deb822 releases (24.04+) are deliberately excluded: there the primary mirror above
-        # already lands in /etc/apt/sources.list.d/ubuntu.sources, so adding these legacy .list
-        # files would configure the same suites twice.
+        # On 20.04/22.04 Subiquity renders the target's sources.list from the install media
+        # alone, so in-target apt cannot find packages the ISO does not carry (chrony). Add the
+        # online archive through `sources:` -- `sources_list:` is a curtin key Subiquity's
+        # schema ignores. Excluded on Deb822 releases, where the primary mirror already lands
+        # in ubuntu.sources and these legacy .list files would duplicate the same suites.
         my $need_sources_block = !$use_deb822;
         if ($need_sources_block) {
             push @lines, '    sources:';
diff --git a/xCAT-server/lib/xcat/plugins/debian.pm b/xCAT-server/lib/xcat/plugins/debian.pm
index 4c7987195..1b039836d 100644
--- a/xCAT-server/lib/xcat/plugins/debian.pm
+++ b/xCAT-server/lib/xcat/plugins/debian.pm
@@ -513,25 +513,18 @@ sub copycd
 
     Build the kernel command line for a Subiquity (Ubuntu live installer) diskful install.
 
-    boot=casper is required: without it casper never processes netboot=nfs, it scans the local
-    disks, finds no live media and panics "Unable to find a medium containing a live file
-    system" (initramfs emergency shell -> PXE loop).
+    boot=casper: without it casper never processes netboot=nfs -- it scans the local disks,
+    finds no live media and panics into the initramfs shell, which PXE-loops.
 
-    nfsroot MUST be a literal IP: casper mounts the live filesystem with klibc's nfsmount, which
-    cannot resolve hostnames ("nfsmount: can't parse IP address '<host>'"). The ds= URL is
-    fetched later by cloud-init in the booted live system where normal DNS works, so it keeps
-    the install server's name.
+    nfsroot must be a literal IP: casper mounts the live filesystem with klibc's nfsmount,
+    which has no resolver. The ds= URL is fetched later by cloud-init, where DNS works, so it
+    keeps the install server's name.
 
-    'toram' makes casper copy the live squashfs into RAM and UNMOUNT the NFS source (casper
-    scripts/casper: copy_to_ram then umount of the copy source), so the installer runs from RAM
-    with NO network root. This is what lets the node reboot at all: with the NFS root still
-    mounted, a process doing I/O to it during systemd-shutdown (lvm, netplan, udev) blocks in
-    uninterruptible D state -- it cannot be SIGKILLed, so systemd-shutdown waits forever
-    ("Waiting for process: <pid> (lvm)") and the node never power-cycles into the disk it just
-    installed. casper has no cmdline knob for NFS mount options -- it parses only nfsroot=,
-    taking the whole value as the path, so appending ,soft breaks the mount; toram is casper's
-    supported way to avoid the network root. The 24.04 layers total ~1.5G, well within the CN's
-    RAM.
+    toram: casper copies the squashfs to RAM and unmounts the NFS source, so nothing holds the
+    network root at shutdown. Without it a process doing I/O to it blocks uninterruptibly,
+    systemd-shutdown waits forever and the node never reboots into the disk it just installed.
+    casper parses only nfsroot= and takes the whole value as the path, so mount options cannot
+    be appended; toram is its supported alternative.
 
     Arguments:
         $base       the command line built so far
diff --git a/xCAT-server/share/xcat/install/ubuntu/compute.subiquity.tmpl b/xCAT-server/share/xcat/install/ubuntu/compute.subiquity.tmpl
index 547a48aa1..783ebc2de 100644
--- a/xCAT-server/share/xcat/install/ubuntu/compute.subiquity.tmpl
+++ b/xCAT-server/share/xcat/install/ubuntu/compute.subiquity.tmpl
@@ -66,12 +66,9 @@ autoinstall:
       sed -i '/^\.\.\.$/d' /autoinstall.yaml
       cat /tmp/partitionfile >> /autoinstall.yaml
       echo "=== DNS setup ==="
-      # A nameserver line in /etc/resolv.conf MUST hold an IP address -- glibc's resolver does
-      # NOT resolve a hostname written there, it discards the entry. Writing the xcatmaster
-      # *name* leaves the installer (and the in-target apt-get, which inherits this file) with
-      # no usable DNS, so the install hangs resolving archive.ubuntu.com. DNS still works at
-      # this point through the live installer's DHCP resolv.conf -- the wget calls above relied
-      # on it -- so resolve the xcatmaster to an IPv4 address first and write that.
+      # glibc's resolver discards a nameserver line naming a host, so writing the xcatmaster
+      # *name* leaves the installer -- and the in-target apt that inherits this file -- with no
+      # DNS. Resolve it here, while the live installer's DHCP resolv.conf still works.
       xcatmaster_host="#TABLE:noderes:$NODE:xcatmaster#"
       xcatmaster_ip="$(getent ahostsv4 "$xcatmaster_host" | awk '{print $1; exit}')"
       [ -n "$xcatmaster_ip" ] || xcatmaster_ip="$xcatmaster_host"
@@ -110,16 +107,10 @@ autoinstall:
     cp ./#HOSTNAME#.post /target/root/post.script;
     curtin in-target --target /target /root/post.script;
     } >>/target/var/log/xcat/xcat.log 2>&1'
-    # Switch the node to boot from the local disk now the install is done, or it PXE-loops
-    # straight back into the installer when Subiquity reboots. xCAT flips the netboot state
-    # when the node reports "next" to xcatd on the install-monitor port, which makes xcatd run
-    # "nodeset <node> next" and rewrite the node's xNBA script to fall through to local disk.
-    # The in-target post-script tries this through updateflag.awk, but that needs gawk's |&
-    # /inet coprocess and /usr/bin/awk on Ubuntu is normally mawk, so the flip silently fails.
-    # Send it from the live installer instead -- the connection then originates from the node's
-    # own IP, which xcatd trusts -- using bash's built-in /dev/tcp, with no gawk dependency.
-    # xcatd answers with a ready token, takes "next", and acknowledges; treat anything else as
-    # a failure and say so in the install log rather than rebooting into another install.
+    # Flip the node to local-disk boot, or it PXE-loops back into the installer on reboot.
+    # The in-target post-script does this through updateflag.awk, which needs gawk's |& and
+    # Ubuntu's /usr/bin/awk is mawk, so it silently failed. Send "next" to xcatd from the live
+    # installer over bash's /dev/tcp instead, and log a failure rather than reinstalling.
     - ['bash', '-c', 'xm=#XCATVAR:XCATMASTER#; ok=0; for i in 1 2 3 4 5; do if exec 3<>/dev/tcp/$xm/3002; then read -r r <&3 || true; printf "next\n" >&3; if read -r r <&3; then ok=1; fi; exec 3>&- 3<&-; [ "$ok" = 1 ] && break; fi; sleep 5; done; if [ "$ok" != 1 ]; then echo "xcat: FAILED to flip $(hostname) to local-disk boot via $xm:3002; the node will PXE back into the installer" >>/target/var/log/xcat/xcat.log; fi; exit 0']
   error-commands:
     - tar -c --ignore-failed-read --transform='s/^/#HOSTNAME#-logs\//' /var/crash /var/log/installer /tmp/pre-install.log /autoinstall.yaml 2>/dev/null |nc -l 8080
diff --git a/xCAT-test/unit/ubuntu_subiquity_apt_sources.t b/xCAT-test/unit/ubuntu_subiquity_apt_sources.t
index f857af48e..0c55d0e8c 100644
--- a/xCAT-test/unit/ubuntu_subiquity_apt_sources.t
+++ b/xCAT-test/unit/ubuntu_subiquity_apt_sources.t
@@ -8,18 +8,9 @@ use lib "$FindBin::Bin/../../xCAT-server/lib/perl";
 
 use Test::More;
 
-# Regression: on an ONLINE Subiquity install of a classic-sources release (20.04 / 22.04),
-# Subiquity renders the target's /etc/apt/sources.list from the install media alone
-# ("deb file:///cdrom"). A live-server ISO does not carry everything xCAT's postscripts need --
-# chrony, for one -- so curtin's in-target apt fails with "E: Unable to locate package chrony"
-# and the install crashes. `sources_list:` is a curtin key that Subiquity's autoinstall schema
-# ignores, so the online archive has to be added through `sources:`, which Subiquity honours by
-# writing /etc/apt/sources.list.d/*.list.
-#
-# That fix belongs to the classic-sources releases ONLY. On a Deb822 release (24.04 / 26.04)
-# the primary mirror already lands in /etc/apt/sources.list.d/ubuntu.sources, so adding legacy
-# .list files on top produces duplicate apt entries for the same suites -- exactly the source
-# conflict the Deb822 branch elsewhere in this function goes out of its way to avoid.
+# An online Subiquity install of a classic-sources release needs the online archive added, or
+# in-target apt cannot find chrony and the install crashes. A Deb822 release must NOT get it,
+# or the same suites are configured twice. See the comment in Template.pm.
 
 require xCAT::Template;