Learn Portuguese (Portugal): O carregador deste computador é muito avançado. - The charger of this computer is very advanced.

In Portuguese, the preposition de (of) must combine with the demonstrative pronoun este (this). So, de plus este becomes deste (of this). This contraction is mandatory, not optional!

Why use é (from the verb ser) instead of está (from estar) here?

We use ser for permanent or inherent characteristics. Being advanced is a core design feature of this specific charger, rather than a temporary condition like being hot or broken.

Does the adjective avançado agree with carregador or computador?

It agrees with o carregador (the charger), which is the main subject of the sentence. Because carregador is a masculine, singular noun, the adjective takes the masculine, singular ending -o.

If I wanted to use the textual connector no entanto to say 'However, it is heavy', where would it go?

You would typically place it after a comma or semicolon to introduce the contrasting idea. For example: O carregador deste computador é muito avançado, no entanto, é pesado. You could also use porém in the exact same spot.