@hellomiakoda A couple of these seem promising. The Linux Questions one got some in-depth replies. It sounds like a config file problem to me, but I've not used SuSE in a long time, so this is about the extent of my usefulness here (if any).
https://noai.duckduckgo.com/?hps=1&q=open+suse+nfs+access+denied+by+server&atb=v448-1&ia=web