diff --git a/CLIENTS/README.md b/CLIENTS/README.md
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+# Downstream Linux PTP Clients
+
+This directory contains the reusable Linux configuration for servers downstream from NEXUS switch.
+
+The intended path is:
+
+```text
+RPi5 Grandmaster
+      │
+      \/
+Linux Boundary Clock
+      │
+      \/
+Nexus Boundary Clock
+      │
+      \/
+Linux client NIC PHC
+      │
+   phc2sys
+      │
+      \/
+CLOCK_REALTIME (UTC)
+```
+
+Each direct client normally needs only:
+
+1. `ptp` enabled on its physical NEXUS switch port;
+2. `ptp4l` to synchronize the NIC PHC from NEXUS; and
+3. `phc2sys` to synchronize Linux `CLOCK_REALTIME` from that PHC.
+
+## Files in this directory
+
+| File | Install as | Purpose |
+|---|---|---|
+| `ptp4l-client.conf` | `/etc/linuxptp/ptp4l-client.conf` | Ordinary-clock/client-only PTP configuration |
+| `ptp4l-client.service` | `/etc/systemd/system/ptp4l-client.service` | Runs `ptp4l` on the client NIC |
+| `phc2sys-client.service` | `/etc/systemd/system/phc2sys-client.service` | Synchronizes `CLOCK_REALTIME` from the client NIC PHC |
+
+The bundled files currently use `enp4s0` as the client interface. Change that name everywhere if the target server uses another interface.
+
+## 1. Enable PTP on the corresponding Nexus port
+
+On NEXUS:
+
+```text
+configure terminal
+
+interface Ethernet1/<clientPort>
+  ptp
+
+end
+copy running-config startup-config
+```
+
+Example:
+
+```text
+interface Ethernet1/10
+  ptp
+```
+
+Once the client is online, the Nexus port should normally become `Master` in:
+
+```text
+show ptp brief
+```
+
+## 2. Install LinuxPTP
+
+On the client:
+
+```bash
+sudo apt update
+sudo apt install linuxptp ethtool
+```
+
+## 3. Identify the PTP NIC
+
+Find the interface connected to NEXUS:
+
+```bash
+ip -br link
+```
+
+The examples below assume:
+
+```text
+enp4s0
+```
+
+If your interface has a different name, replace `enp4s0` in all three files before installing them.
+
+For example, search the bundled files with:
+
+```bash
+grep -Rni 'enp4s0' .
+```
+
+## 4. Verify hardware timestamping
+
+```bash
+ethtool -T enp4s0
+```
+
+The NIC should expose hardware transmit, receive, and raw hardware timestamping plus a PTP Hardware Clock.
+
+You can map it to the PHC device with:
+
+```bash
+readlink -f /sys/class/net/enp4s0/device/ptp/ptp*
+```
+
+If the NIC does not support hardware timestamping, do not use the bundled `time_stamping hardware` configuration unchanged.
+
+## 5. Disable competing system-clock synchronization
+
+`phc2sys-client.service` will discipline `CLOCK_REALTIME`. Disable services that would compete for the same system clock:
+
+```bash
+sudo systemctl disable --now chrony 2>/dev/null || true
+sudo systemctl disable --now systemd-timesyncd 2>/dev/null || true
+sudo systemctl disable --now ntp 2>/dev/null || true
+sudo systemctl disable --now ntpd 2>/dev/null || true
+```
+
+## 6. Install the client files
+
+If the interface really is `enp4s0`, install the files directly:
+
+```bash
+sudo install -D -m 0644 ptp4l-client.conf /etc/linuxptp/ptp4l-client.conf
+sudo install -D -m 0644 ptp4l-client.service /etc/systemd/system/ptp4l-client.service
+sudo install -D -m 0644 phc2sys-client.service /etc/systemd/system/phc2sys-client.service
+```
+
+If the interface name is different, edit the local copies first and replace `enp4s0` in:
+
+```text
+ptp4l-client.conf
+ptp4l-client.service
+phc2sys-client.service
+```
+
+The PTP client config intentionally uses:
+
+```text
+domainNumber      0
+network_transport UDPv4
+delay_mechanism   E2E
+clientOnly        1
+```
+
+`clientOnly 1` prevents a downstream server from ever trying to become the grandmaster.
+
+## 7. Enable the services
+
+```bash
+sudo systemctl daemon-reload
+sudo systemctl enable --now ptp4l-client.service
+sudo systemctl enable --now phc2sys-client.service
+```
+
+The data flow is:
+
+```text
+ptp4l:    NEXUS -> NIC PHC
+phc2sys:  NIC PHC -> CLOCK_REALTIME
+```
+
+The bundled `phc2sys` service uses:
+
+```bash
+phc2sys -s enp4s0 -c CLOCK_REALTIME -w -m
+```
+
+`-w` waits for `ptp4l` and obtains the PTP/UTC offset from it, so the client does not need a hard-coded `-37` offset.
+
+## 8. Verification
+
+Check service state:
+
+```bash
+systemctl status ptp4l-client
+systemctl status phc2sys-client
+```
+
+Follow the logs:
+
+```bash
+journalctl -fu ptp4l-client
+journalctl -fu phc2sys-client
+```
+
+`ptp4l` should progress into the synchronized client/slave state and its master offsets should settle near zero.
+
+Query PTP datasets:
+
+```bash
+sudo pmc -u -b 0 'GET PORT_DATA_SET'
+sudo pmc -u -b 0 'GET CURRENT_DATA_SET'
+sudo pmc -u -b 0 'GET PARENT_DATA_SET'
+sudo pmc -u -b 0 'GET TIME_STATUS_NP'
+```
+
+For a client directly downstream from NEXUS, expect approximately:
+
+```text
+portState             CLIENT/SLAVE
+stepsRemoved          3
+grandmasterIdentity   <same RPi5 grandmaster identity>
+```
+
+In the current topology the RPi5 grandmaster identity observed on NEXUS is:
+
+```text
+88a29efffe826ce6
+```
+
+If the RPi5 NIC or grandmaster identity changes later, use the currently advertised identity instead of treating that value as permanent.
+
+Also verify the Nexus side:
+
+```text
+show ptp brief
+```
+
+The client-facing Nexus port should normally be `Master`.
+
+## 9. Quick deployment checklist for another server
+
+```text
+NEXUS:
+  interface Ethernet1/X
+    ptp
+
+Linux server:
+  1. install linuxptp + ethtool
+  2. verify `ethtool -T <NIC>`
+  3. replace `enp4s0` in the three bundled files if needed
+  4. install the config and two systemd units
+  5. disable chrony/timesyncd/ntpd if they discipline CLOCK_REALTIME
+  6. enable ptp4l-client and phc2sys-client
+  7. verify logs + pmc output
+```
+
+## 10. Troubleshooting
+
+If `ptp4l` stays in LISTENING:
+
+```bash
+sudo tcpdump -ni enp4s0 'udp port 319 or udp port 320'
+journalctl -u ptp4l-client -n 100 --no-pager
+```
+
+Then check NEXUS:
+
+```text
+show ptp brief
+show ptp packet
+```
+
+If the NIC PHC synchronizes but Linux system time does not, inspect:
+
+```bash
+journalctl -u phc2sys-client -n 100 --no-pager
+systemctl status chrony systemd-timesyncd ntp ntpd
+```
+
+Only one service should be responsible for disciplining `CLOCK_REALTIME` on the client.
diff --git a/CLIENTS/phc2sys-client.service b/CLIENTS/phc2sys-client.service
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+#  /etc/systemd/system/phc2sys-client.service
+
+
+[Unit]
+Description=Synchronize Linux system clock from PTP PHC
+After=ptp4l-client.service
+Requires=ptp4l-client.service
+
+[Service]
+Type=simple
+ExecStart=/usr/sbin/phc2sys \
+    -s enp4s0 \
+    -c CLOCK_REALTIME \
+    -w \
+    -m
+Restart=always
+RestartSec=3
+
+[Install]
+WantedBy=multi-user.target
diff --git a/CLIENTS/ptp4l-client.conf b/CLIENTS/ptp4l-client.conf
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+# /etc/linuxptp/ptp4l-client.conf
+
+
+[global]
+
+# Use NIC hardware timestamping
+time_stamping           hardware
+
+# Match the rest of your PTP domain
+domainNumber            0
+network_transport       UDPv4
+delay_mechanism         E2E
+
+# This machine must never try to become GM
+clientOnly              1
+
+# Useful logging while setting it up
+summary_interval        1
+
+
+[enp4s0]
diff --git a/CLIENTS/ptp4l-client.service b/CLIENTS/ptp4l-client.service
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+# /etc/systemd/system/ptp4l-client.service
+
+
+[Unit]
+Description=PTP client on enp4s0
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+Type=simple
+ExecStart=/usr/sbin/ptp4l \
+    -i enp4s0 \
+    -f /etc/linuxptp/ptp4l-client.conf \
+    -m
+Restart=always
+RestartSec=3
+
+[Install]
+WantedBy=multi-user.target