Из-за слабого сигнала приложение работало медленно.

slowly

Breakdown of Из-за слабого сигнала приложение работало медленно.

• работать: to work
• приложение: the application
• из-за: because of

Questions & Answers about Из-за слабого сигнала приложение работало медленно.

Why is it слабого сигнала and not, for example, слабый сигнал?

Because the compound preposition из‑за always takes the genitive case. Сигнал is a masculine noun, so its genitive singular is сигнала, and the adjective must agree in case, number, and gender: слабого сигнала. More examples:

• из‑за дождя (because of the rain)
• из‑за пробки (because of a traffic jam)

How is из‑за spelled and what exactly does it mean?

• Spelling: always with a hyphen and a space after it: из‑за
  • [GENITIVE].
• Meanings: 1) Causal: из‑за слабого сигнала = because of a weak signal (common in this sentence). 2) Spatial: из‑за угла = from behind the corner. Never write it as из за (no hyphen) or replace it with из here; из alone doesn’t express cause.

Can the cause phrase move? Is Приложение работало медленно из‑за слабого сигнала also correct?

Yes. Russian word order is flexible. Both are natural:

• Из‑за слабого сигнала приложение работало медленно. (fronted cause for emphasis)
• Приложение работало медленно из‑за слабого сигнала. (neutral flow; places new info at the end) Choose position for emphasis and flow; no comma is needed in either version.