Modem mất kết nối.

Literally:

• mất = lose
• kết nối = connection / connectivity

So mất kết nối literally means lose connection. In natural English, this is usually is disconnected, lost connection, or has lost its connection.

Vietnamese does not use articles like a, an, or the the way English does.

So modem can mean:

• a modem
• the modem
• my modem
• that modem

depending on context.

If the speaker wanted to be more specific, they could say things like:

• cái modem này = this modem
• modem của tôi = my modem

But in many everyday situations, just Modem mất kết nối. is perfectly natural.

It is a loanword used in Vietnamese. Many technology terms are borrowed from English, especially in casual speech.

So modem in Vietnamese is basically the same item as English modem. Depending on the speaker, you may hear it pronounced in a more Vietnamese way, but the written form is usually still modem.

Mất often means to lose, but it is also commonly used to mean that something is gone, no longer present, or stopped working/available in some way.

For example:

• mất điện = the power is out
• mất mạng = the internet/network is down
• mất tín hiệu = lost signal
• mất kết nối = lost connection

So here, mất does not mean the modem physically lost an object. It means the modem no longer has connection.

Here it is best understood as a noun-like expression meaning connection.

• kết nối can refer to connection/connectivity
• As a verb, it can also mean to connect

In mất kết nối, the whole phrase behaves like lose connection.

So you can think of it as:

• mất = lose
• kết nối = connection

Vietnamese usually does not mark tense directly on the verb the way English does. The time is often understood from context.

So Modem mất kết nối. could mean:

• The modem lost connection
• The modem has lost connection
• The modem is disconnected

Which English version is best depends on the situation.

If Vietnamese speakers want to make time clearer, they can add words like:

• đã = past/completed
• đang = in progress
• sẽ = future

For example:

• Modem đã mất kết nối. = The modem has lost connection / lost connection.

Yes. It is short, natural, and very common in speech or system-style messages.

Vietnamese often allows short subject + predicate sentences without extra words. This one is straightforward:

• Modem = subject/topic
• mất kết nối = predicate

It sounds like something you might say when troubleshooting internet problems.

Yes, Modem bị mất kết nối is also possible, but it has a slightly different feel.

• Modem mất kết nối = simple, direct, neutral
• Modem bị mất kết nối = adds a sense that the modem was affected by an unwanted problem

The word bị often marks something negative or adverse happening to the subject.

In many everyday cases, the version without bị is more concise and more common.

A rough guide:

• modem: often pronounced somewhat like mô-dem in Vietnamese speech
• mất: short vowel, with a heavy/falling tone
• kết: also a short vowel with a heavy/falling tone
• nối: rising tone

If you want a rough learner-friendly approximation:

• mô-dem mất kết nối

The most important part is getting the tones right on:

• mất
• kết
• nối

because tone mistakes can make you harder to understand.

You could, but it does not mean exactly the same thing.

• Modem mất kết nối = The modem lost connection / became disconnected
• Modem không kết nối = The modem does not connect / is not connecting

The second one sounds more like a general failure to connect, while mất kết nối suggests there was a connection and then it was lost.

You can make it more specific in several ways:

• Modem nhà em mất kết nối rồi. = My home modem has lost connection.
• Cái modem này mất kết nối rồi. = This modem lost connection.
• Modem bị mất kết nối với mạng. = The modem lost connection to the network.

A very common conversational addition is rồi, which often suggests that the change has already happened:

• Modem mất kết nối rồi. = The modem has lost connection now / already.

Grammatically, it says the modem has lost connection. In real life, that often implies an internet or network problem, but the sentence itself focuses on the modem’s connection status.

Depending on context, it could mean:

• the modem lost connection to the ISP
• the modem lost connection to the network
• the device is no longer online

So the exact technical meaning depends on the situation, but the grammar is simply saying that the modem is no longer connected.