The ETravelSim Portugal eSIM works in the main Douro Valley villages including Pinhão, Peso da Régua, and the Quinta wine estates with reliable 4G at accommodations and main roads. Signal can drop briefly on the Douro train between vineyards and on river boat sections through narrow gorges. Alentejo plains around Évora, Monsaraz, and Marvão have generally good 4G coverage at towns and main roads, but thinner signal at remote farms and cork-oak forests. Save offline maps before remote wine tours.