ERR_CONNECTION_RESET when accessing Nextcloud from the Internet

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Hello

I am having trouble accessing my Nextcloud installation from the internet. I installed Nextcloud on Windows 11 / Docker Desktop according to these instructions: GitHub - nextcloud/all-in-one: 📦 The official Nextcloud installation method. Provides easy deployment and maintenance with most features included in this one Nextcloud instance.

The setup went smoothly and I can also access Nextcloud on the LAN (browser / Windows client / Android app).

Unfortunately, it doesn’t work from outside. The browser displays the error message ERR_CONNECTION_RESET.

In the router port 443 is forwarded to the Windows computer running Docker/Nextcloud. I use a DynDNS service from softether.net.

Edit: According to https://www.yougetsignal.com/tools/open-ports/ Port 443 is open. My public IP starts with 185. Therefore I assume that my ISP is not blocking 443 or using CGNAT.

Nextcloud is version “Nextcloud AIO v12.3.0” and has the following errors in the logs:

Fehlersuche admin_audit RuntimeExceptionThe loading of lazy AppConfig values have been triggered by app “admin_audit” 31.12.2025, 00:23:35
Fehler core ExceptionHMAC does not match. 30.12.2025, 23:54:53
Fehler core ExceptionHMAC does not match. 30.12.2025, 23:54:53
Fehler core NotFoundException/appdata_ockknz5bfnsv/theming/global 30.12.2025, 23:40:14
Fehler core NotFoundException/appdata_ockknz5bfnsv/theming/global 30.12.2025, 23:40:14
Warnung no app in context Skipping updater backup clean-up - could not find updater backup folder /nc-updater/updater-ockknz5bfnsv/backups 30.12.2025, 23:40:13
Warnung no app in context Skipping updater backup clean-up - could not find updater backup folder /nc-updater/updater-ockknz5bfnsv/backups 30.12.2025, 23:40:13
Warnung cron QueryNotFoundExceptionCould not resolve OCA\AppAPI\BackgroundJob\ExAppInitStatusCheckJob! Class “OCA\AppAPI\BackgroundJob\ExAppInitStatusCheckJob” does not exist 30.12.2025, 23:40:08
Warnung cron QueryNotFoundExceptionCould not resolve OCA\AppAPI\BackgroundJob\ExAppInitStatusCheckJob! Class “OCA\AppAPI\BackgroundJob\ExAppInitStatusCheckJob” does not exist 30.12.2025, 23:40:08
Fehlersuche admin_audit RuntimeExceptionThe loading of lazy AppConfig values have been triggered by app “admin_audit” 30.12.2025, 23:38:18
Fehlersuche admin_audit RuntimeExceptionThe loading of lazy AppConfig values have been triggered by app “admin_audit” 30.12.2025, 23:38:18

Thanks in advance.

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Hi, this might be a ipv6 problem. Did you set an AAAA record for your domain?

3

No, I don’t hve an AAAA record, but I don’t have a public ipv6.

4

I don’t use Windows. But can you access port 443 of your Windows computer from another computer on the same network? If not, it sounds to me like a Windows firewall problem.

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Yes, I can access port 443 from another computer in the same network. In my LAN everything works well, the problem occurs when I try to access from the internet.

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Hi @florian.b,

I suspect the problem lies right here:

Could you please tell us which router you’re using and how you configured port forwarding?

It might also be helpful to know the topology of your local network.

ernolf

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Hi @ernolf

I assume you are right. In the meantime I set up a Nextcloud AIO on a virtual debian machine, and I’m getting the same results. Rechable (over the DNS-Name from softether) from the LAN but not from the internet.

The router is a EG8147X6.

These are the port forwarding settings:

image
image701Ă—505 14.1 KB

The Windows machine with Docker Desktop is connect via TP-Link BE65 in access point mode.
The Debian VM runs on a host directly connected to router. The network mode (Oracle Virtual Box) is Bridged Adapter.

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I know you didn’t ask for my opinion, but the Huawei EG8147X6 is crap. Huawei makes routers that restrict port forwarding to just a few ports: 7777, 8888, 8080, and 8000. I don’t know if that’s the case with your router, of course, but you could try forwarding port 8888 externally to port 443 internally and see if you can connect via

https://yourdyndnsname:8888

Is your dyndnsname in the list of trusted hosts?

If that does not work either, try it with a proper router, at least a Fritz!Box or something similar, instead of a $20 toy from Alibaba :wink:

Good luck!

h.t.h.

ernolf

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That’s the router my ISP provided …

I got an VPN running in the same network and I’m forwarding other ports to it, and that works. Still tried with 8888 but with the same result.

Yes, my dyndns is in the trusted hosts.

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