For anyone else finding this thread, the comments attached to this article (https :// www .portugalist. com /portugal-atms-guide) seem like they may have the answer for those who cannot find the larger banks. I'll try to summarize my understanding in hopes of helping others avoid the ridiculous ATM fees I've been encountering. Still, I would recommend reading the comments on that article to gain a more thorough understanding.

If you go up to a Portuguese ATM and put in your card, you're going to be offered an absolutely horrendous rate (13.00% or so.) It will ask if you want to accept this rate. YOU MUST SAY 'NO' or select the option to REJECT the rate. It will likely show you a second screen that has some confusing information saying you've declined the rate and threatening you with an "unknown" rate or something like that. It again will be offering you the absurdly terrible rate that you saw originally. You need to say NO again (or reject their rate) -- read carefully because they're trying to trick you into clicking the button that will approve them to charge you your rate.

On one of these screens you should see the option to REJECT their scam rate and instead be charged the "unknown" rate. That unknown rate should be the market rate for exchanges, and will be MUCH more favorable.

To be clear, you'll still be charged the ATM charge (probably something like 4€ to 8€ if I had to guess) which is why you should use a card that refunds those fees worldwide, but the exchange rate will be much, much better.

Frankly I'm pretty appalled that the banking laws in Portugal allow for this dubious behavior. I've taken money out of sketchy looking ATMs in about 5 different countries, and at larger ATMs directly across from some of the largest tourist traps in Europe. Never before have I experienced such an abusive, and misleading process as I've encountered at every single ATM I've visited in Portugal. I hope that this type of abuse comes under legislative review at some point.