waipaiga eobseumyeon inteonesi jal an dwaeyo.

Korean often uses two -이/가 phrases when one sets a condition/background and the other is the main thing being described.

• 와이파이가 없으면 = If there is no Wi‑Fi… (condition)
• 인터넷이 잘 안 돼요 = the internet doesn’t work well. (main statement)

So it’s basically: If Wi‑Fi isn’t available, the internet doesn’t work well.

없으면 is 없다 (to not exist / to not have) + the conditional ending -(으)면 (if/when).

• Verb/adjective stem: 없-
• • 으면 (because the stem ends in a consonant) → 없으면 = if there isn’t / if you don’t have

You can use -(으)면 with many verbs/adjectives:

• 시간이 있으면 = if I have time
• 비가 오면 = if it rains

The particle -이/가 marks 와이파이 as the subject of 없다 (there is no Wi‑Fi).
In casual speech, particles are sometimes dropped, but including them is clearer and more standard:

• Standard/clear: 와이파이가 없으면
• More casual: 와이파이 없으면

Here 잘 means well/properly/smoothly. With 안 되다 it often means “work properly.”

• 잘 돼요 = it works well / it goes well
• 잘 안 돼요 = it doesn’t work well / it doesn’t go well

It does not mean “often” here.

Both are seen, but spacing rules usually treat 안 (short-form negation) as separate:

• Recommended spacing: 안 돼요
• Common in real life: 안돼요

Meaning is the same. In writing practice, 안 돼요 is a safe choice.

되다 literally means to become / to be done, but in many situations it means to work / to function / to go through. So:

• 인터넷이 돼요 = the internet works / it’s working (e.g., connection is functioning)
• 인터넷이 안 돼요 = the internet doesn’t work (no connection / not functioning)

It’s a very common pattern for devices/services:

• 결제가 안 돼요 = the payment won’t go through
• 프린터가 안 돼요 = the printer doesn’t work

The base verb is 되다. When conjugated to 해요체, it becomes 되어요, which contracts to 돼요:

• 되다 → 되어요 → 되어요 → 돼요 (common contraction)

되요 is a very common misspelling, but the standard spelling is 돼요.

…돼요/안 돼요 is polite informal (해요체)—very common in daily conversation. Alternatives:

• More formal polite: 인터넷이 잘 안 됩니다.
• Casual (to friends): 인터넷 잘 안 돼.
• Even more casual: 인터넷 안 돼.

Yes, depending on emphasis.

• 와이파이가 없으면… focuses neutrally on the condition (there is no Wi‑Fi).
• 와이파이는 없으면… can sound like you’re contrasting Wi‑Fi with something else (e.g., As for Wi‑Fi, if there isn’t any…).

Similarly:

• 인터넷이 잘 안 돼요 is neutral.
• 인터넷은 잘 안 돼요 can imply contrast (e.g., The internet (at least) doesn’t work well, but something else might.).

-(으)면 can mean if or when, and the context decides. Here it’s usually understood as if (a condition that may or may not be true):

• 와이파이가 없으면 = If there’s no Wi‑Fi…

But if someone is describing a repeated/typical situation, it can feel like when(ever):

• When there’s no Wi‑Fi, the internet doesn’t work well. (general truth)