I have cleaned 2 'vent' hose ends so far. One in a Forester, the other on an Outback. The vent hose leaves the charcoal canister goes to the "drain Filter" ( round plastic filter mounted above the charcoal canister ).
The OTHER side of the drain filter has a large hose on it that goes thru a TEE ( with a smaller hose on the TEE ). You want to follow that larger hose. I know it's a PITA , but it will lead to a plastic insert above the rear differential housing/mount assy. That's where the air is vented after the fumes are captured in the Charcoal Canister. This allows air out of the tank during gas fillup.
This is also where the tank is vented in ( metered controlled air thru the Vent Valve ) to allow gas to flow out of the tank and not create a vacuum.
I tried to take a picture and attach it. Hope you guys get an idea where it is, and why it's a real pain to get to! 1st pix is on the passenger side just in front of the spare wheel well. The 2nd I tried to get a closeup of the hose going into the white plastic end that's attached to the frame and vents it to the air. This is where I have found the spiders web and debris.
98S, 2014 Impreza 5 dr Ltd (9 Subaru's since 1978, 7 were 5 sp) ILuvSubaru's