ZeroNet cannot be stably used on GCP

### Step 1: Please describe your environment

* ZeroNet version: 0.6.2
* Operating system: google cloud platform, ubuntu
* Web browser: firefox
* Tor status: always/disabled
* Opened port: yes
* Special configuration: -p 15441:15441 -p 127.0.0.1:43110:43110

### Step 2: Describe the problem:

#### Steps to reproduce:

1. I could visit my ZeroNet site just for 3 seconds, then the connection lost
2. then "FileServer Checking port 15441"
3. finally is stays "FileServer Trying to open port using UpnpPunch"

#### Observed Results:

```[04:57:00] FileServer Trying to open port using UpnpPunch...
[04:57:05] FileServer Internet offline
[04:57:35] ChartCollector Collector connection_ping_min error: min() arg is an empty sequence
[04:57:37] - UiWSGIHandler error: error: [Errno 32] Broken pipe in UiServer.py line 40 > pywsgi.py line 909 > pywsgi.py line 895 > pywsgi.py line 737 > pywsgi.py line 726 > pywsg
i.py line 701 > _socket2.py line 419 > _socket2.py line 355 > _socket2.py line 323
[04:57:37] - UiWSGIHandler error: error: [Errno 32] Broken pipe in UiServer.py line 40 > pywsgi.py line 909 > pywsgi.py line 895 > pywsgi.py line 737 > pywsgi.py line 726 > pywsg
i.py line 701 > _socket2.py line 419 > _socket2.py line 355 > _socket2.py line 323
[04:58:50] FileServer Internet online
[04:58:51] FileServer Checking port 15441 using portchecker.co...
[04:58:51] FileServer Checking port 15441 using canyouseeme.org...
[04:59:00] FileServer [BAD :(] Port closed: Error: I could not see your service on 35.195.180.250 on port (15441) Reason: Connection timed out
[04:59:00] FileServer Trying to open port using UpnpPunch...```

#### Expected Results:

Could it be used stably on google cloud platform? Thanks!

Start with the FileServer port-checking and UpnpPunch flow described in the report, then inspect the referenced UiServer.py, pywsgi.py, and _socket2.py stack entries. Compare the behavior with GCP port 15441 and the reported Internet offline, broken pipe, and connection-timeout messages; done means ZeroNet remains reachable stably on GCP.

索引モデルが issue の本文から書いたものです。