I have another solution for you, @WhiteTom and @zisuu! By the way, this solved the problem for me as well, once and for all. The “router solution” was just an unfortunate coincidence.
Look at this topic:
I noticed that I had very slow login times as well. As it seems, one of our Nextcloud clients at home spammed incorrect login attempts and Nextcloud slowed down all of us (due to the same IP address) to a crawl. I had to wait approximately 30s to log in via the Web interface. Turns out mobile and desktop sync clients hate this and respond with “Operation cancelled”. This also explains the strange fact that Nexcloud started working all of a sudden when I switched to my employer’s VPN network - I switched to an IP address that wasn’t slowed down.
So, to solve this, you can turn off the brute force detection, but I’d advise against it. I truncated the brute force detection table and made sure that all devices log in correctly. The following topic may help you:
What I don’t like about brute force detection is that the feature is not transparent at all. The following topic contains some improvements that’ll make it in future versions of NC (hopefully):
The “router solution” was just an unfortunate coincidence.
This also explains the strange fact that Nexcloud started working all of a sudden when I switched to my employer’s VPN network - I switched to an IP address that wasn’t slowed down.