These are all great suggestions. I would personally go through this list as well.
I also doubt it’s the ISP. It could be, but would be the last thing I would consider.
Given your setup, there are several areas to investigate to resolve the issue of your Bitcoin Core node not receiving inbound connections. Here are some suggestions:
1. **Double-Check Port Forwarding:**
- Ensure that your router's port forwarding rules are correctly set up for port 8333 on both TCP and UDP. Sometimes, port forwarding settings can be tricky, and a small mistake can cause issues.
- Verify that the internal IP address specified in the port forwarding rule is the correct IP address of the machine running the Bitcoin Core node.
2. **Router Configuration:**
- Make sure your router is not using Carrier-Grade NAT (CGNAT), which can sometimes interfere with port forwarding.
- Ensure that there are no additional firewall settings on the router that might be blocking incoming connections.
3. **Local Firewall:**
- Verify that Windows Defender Firewall has the correct inbound rules for both Bitcoin Core and port 8333. Sometimes, the rules might need to be more specific or duplicated for different network profiles (Private, Public, Domain).
4. **ISP Blocking:**
- Although less common, some ISPs might block certain ports or traffic types. Since you mentioned you’re on a shared office building wifi, the network administrator might have certain ports blocked.
- If possible, contact the network administrator or ISP to confirm if port 8333 is being blocked.
5. **Testing Connectivity:**
- Use a port checking tool like [canyouseeme.org](https://canyouseeme.org) to see if port 8333 is accessible from the internet. This will help determine if the port forwarding is working correctly.
- You can also use tools like `telnet` or `nc` (netcat) from an external machine to test if port 8333 is open.
6. **Bitcoin Core Configuration:**
- Ensure that your Bitcoin Core node is configured to accept incoming connections. Check your `bitcoin.conf` file for the following settings:
```plaintext
listen=1
port=8333
bind=
```
- Also, ensure that the `maxconnections` setting allows for a reasonable number of inbound connections.
7. **Alternative Network Setup:**
- Since you're running off a shared office building wifi, consider testing with a different network (e.g., a home network or mobile hotspot) to rule out any network-specific issues.
8. **UPnP and NAT-PMP:**
- Ensure that Universal Plug and Play (UPnP) and NAT Port Mapping Protocol (NAT-PMP) are enabled on your router. Bitcoin Core can use these protocols to automatically configure port forwarding.
By systematically checking each of these areas, you should be able to pinpoint the issue preventing inbound connections to your Bitcoin Core node.
Discussion
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