Add debug ping

.gitea/workflows/publish-image.yaml

@@ -21,6 +21,20 @@ jobs:
     needs: setup
     runs-on: ubuntu-latest
     steps:
+      - name: Debug Network MTU
+        run: |
+          echo "--- Network Config ---"
+          ip link
+          
+          echo "--- Testing Standard Packet (1400 bytes) - Should PASS ---"
+          ping -c 4 -M do -s 1400 github.com || echo "1400 failed"
+          
+          echo "--- Testing Edge Packet (1450 bytes) - Should FAIL on Overlay ---"
+          ping -c 4 -M do -s 1450 github.com || echo "1450 failed as expected"
+          
+          echo "--- Testing Full Packet (1472 bytes) - Should FAIL on Overlay ---"
+          ping -c 4 -M do -s 1472 github.com || echo "1472 failed as expected"
+
       - name: Checkout
         uses: actions/checkout@v3