Simplified form of 岡. Phonosemantic compound. 山 represents the meaning and 网 represents the sound. The traditional component 山 was removed for simplification.
Shuowen Jiezi
《說文》：“网，庖犧所結繩以漁。从冂，下象网交文。，网或从亡；，网或从糸；，古文网；，籀文网。”
Components
山(deleted) — The traditional component 山 was removed for simplification.