Just in case anyone else stumbles onto it, I had problems setting up Ecowitt GW1000 for my use case: climate automation that starts by Ecowitt GW1000 regularly reporting the temperature readings to my custom script (hosted as an Azure Function, but that doesn't matter). So here's a little guide for future self or anyone else who this might help.
1. Plug in the device.
2. Install the "WS View" app on your Android or iOS device. For me personally their Android app did not work when pairing, but others say it's fine.
3. Click the hamburger and choose "Configure New Device" (or maybe you won't have to if you just installed the app).
4. Choose the image of your device, click Next.
5. Follow the instructions on screen (hold the line of LEDs on the device that doesn't seem to be a button until it flashes rapidly in red). Check the checkbox, click Next.
6. When instructed, manually go to Settings, choose the GW** Wifi hotspot and return to the app.
7. The app should report the device as set up.
8. Close the app properly, reopen it, go to the hamburger, Device List.
9. Wait for the device to be discovered, when it is - click on it.
10. Click More in the top right corner, choose Weather Services.
11. Click Next until you get to "Customized"
12. Click Enable, leave protocol at Ecowitt.
13. Enter your hostname (not URL, so no https:// or http:// here, and no path, no port), or the IP. That's the server that hosts your script. Example: user123.randomscripthost.com
14. Enter the Path, starting with a slash "/". Example: /api/v1/mymegaapi/method
15. Leave the port at 80 or change if needed. I believe this thing can only send HTTP requests, and you're out of luck with HTTPS, and simply setting port 443 won't work. So make sure your server is configured to accept HTTP requests (many aren't nowadays unless you override this server-side).
16. Click Save. It must give you an animation that it's saved. If not, properly close the app and start from #8
17. Very important to also go back, click More again, click Device Settings and there click Reboot Device. Without that step my device didn't correctly resolve the hostname via DNS and simply sent all the requests to the gateway (router IP), which has driven me nuts for a couple of days!
18. Done! But if you're still not seeing requests come in server-side, good ways to debug:
a) Configure it (via steps above) to send requests to your local PC where you can set up a server for that port and monitor requests. I did that by installing and running
https://www.npmjs.com/package/http-echo-server (requires installation of Node.js)
b) On your Windows 10 laptop, click the button in the bottom right to bring up the notification area and turn on the Mobile hotspot. You can see the name and password if you press Start and start entering "Mobile hotspot settings". Then you can reset Ecowitt to factory settings and reconfigure it to this wi-fi hotspot on your laptop, and then you can monitor any incoming requests via Wireshark. That's how I knew the device was sending requests to the incorrect IP and didn't even try to run DNS queries (which looks like it only does after reboot). Make sure to choose the correct network adapter - that won't be your normal WiFi network, and instead a new one.
19. If all else fails, also may help to reset the device to factory settings through the app (that's how I reconfigure it to a new WiFi hotspot) AND/OR update firmware (also through the app).
Hope this helps anyone that has trouble with ecowitt customized server not sending requests properly.
Also, by way of 18 b there may be a way to figure out how to get the temperature from the device directly (like, point your Raspberry Pi to it and have it poll the sensor constantly and then run any automation). Not sure if it's been figured out already, but Wireshark can probably capture those packets if you connect both the weather station and your iOS device to your laptop wi-fi access point and monitor packets on the correct network adapter.