Zyxel router custom hash algorithm [duplicate]

My router/access-point Zyxel nwa1123-ac pro stores passwords internally with a custom hashing algorithm. This is the resulting hash for the password “admin”:

$ 4$ fmNgdX1E$ mjanLAViUqqFtmlNhOl2lfQMpOE7LOeV3uk72A5zp+h8H2rsxFGz/DBA9Bz2BO2gOzqnDuvLNx/xzbDMqTSu3HVY9gvkgefDDHQ4gFur6YQ

I couldn’t find any similarities with existing hashing algorithms. There has been some precedent with Zyxel and not so secure password storage: ns3-zyxel