Add iptables fix instructions for n8n-OpenHands connectivity

Final configuration:
- OpenHands: --network=host (can reach runtime containers)
- n8n: bridge network
- Solution: iptables rule to allow bridge→host on port 3000

iptables-fix-instructions.txt

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+## REQUIRED: iptables Fix for n8n → OpenHands Communication
+
+### The Problem:
+Docker containers (like n8n) on bridge networks cannot reach services running with `--network=host`
+(like OpenHands) due to Linux firewall rules. This is a Docker security feature.
+
+### The Solution:
+Add an iptables rule to allow Docker containers to access port 3000 on the host.
+
+### Commands to Run:
+
+```bash
+# 1. Add iptables rule to allow Docker containers to reach host port 3000
+sudo iptables -I DOCKER-USER -p tcp --dport 3000 -j ACCEPT
+
+# 2. Verify the rule was added
+sudo iptables -L DOCKER-USER -n -v | grep 3000
+
+# Expected output:
+#     0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:3000
+
+# 3. Make the rule persistent across reboots
+sudo apt install iptables-persistent -y
+sudo netfilter-persistent save
+```
+
+### Verification:
+
+After running the commands, test that n8n can reach OpenHands:
+
+```bash
+# Test from n8n container
+docker exec n8n wget -O- --timeout=5 http://10.10.10.11:3000/api/options/agents
+
+# Should return: ["BrowsingAgent","CodeActAgent","DummyAgent"...]
+```
+
+### What This Does:
+- Adds a rule to the DOCKER-USER chain (Docker's recommended way to add custom rules)
+- Allows TCP traffic to port 3000 from any source
+- Makes the rule permanent so it survives system reboots
+
+### Security Note:
+This rule allows ALL Docker containers to access port 3000 on the host. Since OpenHands
+is already only listening on localhost (not exposed to the internet), this is safe.
+
+### After This Fix:
+1. OpenHands will work with runtime containers (already working) ✅
+2. n8n will be able to call OpenHands API ✅
+3. The n8n workflow can create conversations and execute tasks ✅
+
+### Ready to Test:
+Once you've run these commands and verified connectivity, restart the n8n workflow:
+- It will use the updated JSON (already pushed to git)
+- URL: http://10.10.10.11:3000/api/conversations
+- Should successfully create hello.txt file
+
+---
+
+## Copy-Paste Commands:
+
+sudo iptables -I DOCKER-USER -p tcp --dport 3000 -j ACCEPT
+sudo iptables -L DOCKER-USER -n -v | grep 3000
+sudo apt install iptables-persistent -y
+sudo netfilter-persistent save
+docker exec n8n wget -O- --timeout=5 http://10.10.10.11:3000/api/options/agents