Cannot upload files from iOS

[MaxMatti]

Some files (three JPEGs) do upload just fine, however others (a PDF, a Screenshot that's probably a PNG and three videos) do not. What happens is that after selecting the files, perkeep says "Uploaded 0 (0%)" and then just reload the page with nothing uploaded. Also no new output show up in the terminal where I'm running the server. For the successfully uploaded files it says "Received blob [...]" a few times. Uploading from my PC works just fine.

If there's an iOS-App I would try that but I could not find any download link, just people referring to it in 2014 with no mention since then.

config:

Trying this with my iPad Air with iOS 12.0.1.

Server:

OS: Ubuntu 18.04.4 LTS
perkeepd version: master, 2019-12-27-9a1336816a
Go version: go1.14 (linux/amd64)

Perkeep config:

{
    "auth": "none",
    "listen": ":3179",
    "camliNetIP": "",
    "identity": "[...]",
    "identitySecretRing": "/home/max/.config/perkeep/identity-secring.gpg",
    "blobPath": "/home/max/var/perkeep/blobs",
    "packRelated": true,
    "levelDB": "/home/max/var/perkeep/index.leveldb"
}

The server is behind a NAT+firewall, so the local IP is not equal to the public IP (however I could not set the option camliNetIP to something other than an empty string as the server would not start) and since I'm already using Nginx elsewhere I'm also using it here.

Nginx config:

server {
        listen 443 ssl http2;
        listen [::]:443 ssl http2;

        ssl_certificate [...];
        ssl_certificate_key [...];

        include snippets/extra-ssl-security.conf;

        server_name [...];

        location / {
                proxy_pass http://localhost:3179;

                auth_basic "Login notwendig.";
                auth_basic_user_file /var/www/html/perkeep/.htpasswd;

                # to use websockets:
                proxy_http_version 1.1;
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection "Upgrade";
                proxy_set_header Host $host;
        }
}

With the included file snippets/extra-ssl-security.conf:

ssl_protocols TLSv1.2;
ssl_ciphers [...];
ssl_prefer_server_ciphers on;

add_header Strict-Transport-Security "max-age=31536000; includeSubDomains; preload";

ssl_stapling on;
ssl_trusted_certificate [...];
ssl_stapling_verify on;