the original “Transbordador “ ferry between Caminha and A Guarda stopped being in service since last year September.
there is a watertaxi
https://xacobeotransfer.com/pt/home_pt/
And if they do not sail, go to the restaurant of the Marina in Caminha and find the fisherman, I thought his name was Mario.
in some threads on this forum his name and phonenumber was mentionned.
For me it was too long ago that I was set over by him.
Alternative is walk on along the Minho river To Vila Nova de Cerveira where is the international bridge and walk back about 15 kms to A Guarda or walk on for 15 kms to Valença do Minho where you hit the central route to Santiago .
both lead to where you want to go to .