Document MTU 9000 jumbo frames configuration

- Added MTU 9000 table showing all configured devices
- Added verification commands for checking MTU
- Added important note about bridge + physical interface MTU sync
- Mac Mini, PVE, PVE2, TrueNAS, and router all support jumbo frames

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

CLAUDE.md

@@ -356,7 +356,32 @@ qm set VMID --net0 virtio,bridge=vmbr2
 qm set VMID --net1 virtio,bridge=vmbr3
 ```
 
-- MTU 9000 (jumbo frames) on all bridges
+### MTU 9000 (Jumbo Frames)
+
+Jumbo frames are enabled across the network for improved throughput on large transfers.
+
+| Device | Interface | MTU | Persistent |
+|--------|-----------|-----|------------|
+| Mac Mini | en0 | 9000 | Yes (networksetup) |
+| PVE | vmbr0, enp1s0 | 9000 | Yes (/etc/network/interfaces) |
+| PVE2 | vmbr0, nic1 | 9000 | Yes (/etc/network/interfaces) |
+| TrueNAS | enp6s18, enp6s19 | 9000 | Yes |
+| UCG-Fiber | br0 | 9216 | Yes (default) |
+
+**Verify MTU:**
+```bash
+# Mac Mini
+ifconfig en0 | grep mtu
+
+# PVE/PVE2
+ssh pve 'ip link show vmbr0 | grep mtu'
+ssh pve2 'ip link show vmbr0 | grep mtu'
+
+# Test jumbo frames
+ping -c 1 -D -s 8000 10.10.10.120  # 8000 + 8 byte header = 8008 bytes
+```
+
+**Important:** When setting MTU on Proxmox bridges, ensure BOTH the bridge (vmbr0) AND the underlying physical interface (enp1s0/nic1) have the same MTU, otherwise packets will be dropped.
 
 ### Tailscale VPN