Archer C80 guide to show and disable hidden SIP ALG option.
Archer C80 > search > SIP
Clicking the result opens menu:
But where is SIP ALG? It's actually there, but hidden in code. Use Chrome, developer mode > advanced > alg and paste into console window:
hit enter and SIP ALG option becomes visible (it's enabled by default):
Just disable SIP ALG and that's it.