expression
far beyond one's power; no match for; not at all equal
Fixed negative expression meaning someone or something is completely outmatched or incomparable. Often used with 〜には to mark the superior party. The form 及びもつかない is a common variant.
See also: 及びもつかない
彼の実力には及びもつかない。
I am no match for his ability.
この作品は前作には及びもつかぬ出来だ。
This work is far inferior to the previous one.
及びもつかぬ is a stronger, more emphatic fixed phrase meaning 'not even close' or 'utterly outmatched', while 及ばない is a more common and neutral way to say 'cannot match' or 'is not necessary'.
From 及ぶ (およぶ, 'to reach, to match') + も (emphatic particle) + つく (付く, 'to stick, to be attached') + ぬ (classical negative auxiliary). Literally 'cannot even get close to'; the つく adds a sense of 'not even sticking/adhering', intensifying the negation.