Randomly 'Lost connection to the server'

Software: NextcloudPI
Hardware: Raspberry Pi 3b+
NC version: 14.0.3

so when i’m just browsing on my cloud i get at the top ‘Lost connection to the server’ message, and the page will not be available for few minutes (This site can’t be reached.) and then it gets back on (this goes all day long)… it has nothing to do with my connection.

anyone has similar problem?