For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:M0ses/openSUSE_Tumbleweed/home:M0ses.repo
zypper refresh
zypper install nm-plugin-splitdns
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:M0ses/15.6/home:M0ses.repo
zypper refresh
zypper install nm-plugin-splitdns
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:M0ses/15.5/home:M0ses.repo
zypper refresh
zypper install nm-plugin-splitdns
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:M0ses/15.4/home:M0ses.repo
zypper refresh
zypper install nm-plugin-splitdns