Zagreb: As the capital, Zagreb offers excellent 4G and 5G connectivity throughout the city center, including the historic Upper Town (Gornji Grad) and the bustling Lower Town (Donji Grad). Coverage on the ZET tram network is consistent as it operates entirely above ground. You may experience weaker signals inside older buildings with thick stone walls, but overall performance is highly reliable.

Split: You'll find strong mobile coverage across Split, especially around the Riva promenade and within the main areas of Diocletian's Palace. While the open-air sections of the historic center are well-served, the thick ancient stone walls can weaken the signal inside some restaurants, cellars, or deep within the palace's substructures.

Dubrovnik: Connectivity is very good in most of Dubrovnik, catering to the high volume of visitors. The Old Town has strong outdoor signals, even when walking the famous city walls. However, be aware that the massive stone fortifications and narrow alleyways can significantly reduce signal strength, particularly indoors or in crowded subterranean bars.

Rijeka: Croatia's principal seaport boasts reliable 4G coverage across its urban core and waterfront areas, including the Korzo promenade. The city's hilly topography might lead to occasional spotty coverage in some outlying residential neighborhoods, but connectivity in central and commercial zones is consistently strong.

Zadar: Expect great network performance on Zadar's Old Town peninsula, from the Roman Forum to the modern Sea Organ installation. Similar to other historic coastal cities, indoor coverage can be less consistent inside the ancient stone buildings, but outdoor signal strength is excellent for navigating and staying connected.