first of all: I am sorry that my English is so bad 
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One day I wanted to send a file to a friend. He could not download the file. Even when I tried it, it didn’t work. I don’t know much about troubleshooting or anything else, but I took a look in the console. This is where the error came up:
CORS Missing Allow Origin (XHR GET https://IP/attachments/xxx-xxx-xxx/xxx)
After I added Access-Control-Allow-Origin to everything I saw, that the reason actually lay somewhere completely different.
The status was “Not Found”:
Status: 404 Not Found.
Then I saw why. My Bitwarden/Vaultwarden Docker Instance is running on Port 8080, but I use also a apache Webserver at Standard Port 80/443. But the Problem is: Vaultwarden is redirecting me to: ´https://myip/attachments/xxx…´, but it should redirect me to ´https://myip:8080/attachments/xxx…´. If I copy the redirected Ip and change the Port, I can Download the File… (More or less, since it is encrypted). So can I change something so that it´s working, is it a bug and I have to wait? or is it just not allowed to run another apache instance?
I hope someone can help me