I have a self-hosted NextCloud Server 15.0.2 running under Ubuntu 16.04.5 LTS. I have to redirect the https port for NextCloud from 443 to 4443 because port 443 is already used for another service. I can connect via WebDAV to the NextCloud storage using WinSCP 5.13.7 under Windows 10 version 1809. When I try to connect with the iOS BoxCryptor App 2.37.826 under iOS 12.1.3 it first shows a dialog that the self-signed certificate of the NextCloud server is not trustworthy. After accepting to trust that certificate I get the message that authentication has failed: The given server could not establish a connection using the username an password (error: 41). I get the same authentication error regardless if I try to add a "Nextcloud" or "WebDAV Advanced" provider in the Boxcryptor iOS app.
Username and password are working fine using WinSCP. This is the server and protocol information shown in WinSCP:
Remote system = Apache/2.4.18 (Ubuntu)
File transfer protocol = WebDAV
Cryptographic protocol = TLS/SSL Implicit encryption, TLSv1.2
Encryption algorithm = TLSv1/SSLv3: ECDHE-RSA-AES256-GCM-SHA384, 2048 bit RSA
Compression = No
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Certificate fingerprint
43:0b:36:df:3d:d9:67:6a:ce:11:83:7b:96:2e:2c:74:37:5d:e0:d0
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Can change permissions = No
Can change owner/group = No
Can execute arbitrary command = No
Can create symbolic/hard link = No/No
Can lookup user groups = No
Can duplicate remote files = Yes
Can check available space = Yes
Can calculate file checksum = No
Native text (ASCII) mode transfers = No
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Additional information
The server supports these WebDAV extensions:
1, 3, extended-mkcol
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Total bytes on device = Unknown
Free bytes on device = Unknown
Total bytes for user = 200 MB (209.891.754 B)
Free bytes for user = -3 B
Bytes per allocation unit = Unknown
