duànwǎng yǐhòu jiǎnchá chātóu.

The structure is:

• 断网以后 = after disconnecting the network / after the network is cut off
• 检查插头 = check the plug

So the pattern is:

[Event 1] + 以后 + [Event 2]

This is a very common Chinese way to say after doing X, do Y.

A similar example:

• 吃饭以后休息。
  Rest after eating.

Here, 以后 means after.

It connects the first action or situation to the next one:

• 断网以后 = after disconnecting the network / after the network goes down
• 检查插头 = check the plug

So 以后 is marking time: first one thing happens, then the next thing happens.

Be careful: 以后 can also mean later or in the future in other sentences. For example:

• 以后再说。
  We’ll talk about it later.

But in your sentence, it clearly means after.

In Chinese, time words like 以后 usually come after the event they refer to.

So Chinese says:

• 断网以后 = literally disconnect-network after

English usually says:

• after disconnecting the network

This word order is very normal in Chinese. Compare:

• 下课以后回家。
  Go home after class.
• 吃完饭以后洗碗。
  Wash the dishes after eating.

So even though it feels reversed compared with English, it is standard Chinese grammar.

Yes, the subject is omitted.

Chinese often leaves out the subject when it is obvious from context, especially in:

• instructions
• warnings
• manuals
• procedural steps

So 断网以后检查插头 naturally sounds like an instruction, where the understood subject is something like:

• 你 = you
• or an unspecified person carrying out the procedure

In English, we also do this in instructions:

• Turn off the power. Check the plug.

Chinese does the same thing very often.

Yes, it most likely functions as an instruction or command.

Chinese commands do not need a special verb form. The bare verb can be enough, especially in manuals or notices.

So:

• 检查插头。 = Check the plug.

If you want to make it softer or more polite, Chinese often adds words like:

• 请检查插头。 = Please check the plug.
• 检查一下插头。 = Check the plug for a moment / give the plug a check

So the original sentence sounds brief and instructional.

断网 literally means to cut off the network or to disconnect from the internet/network.

Depending on context, it can mean:

• to intentionally disconnect the network
• for the network to go down
• to cut network access

That said, some learners may notice that 断网 and 检查插头 do not feel like the most natural pair in everyday Chinese. In many real-life technical instructions, you might more often see something like:

• 断电以后检查插头。
  Check the plug after turning off the power.

or

• 断开网络连接以后检查设备。
  Check the device after disconnecting the network connection.

So 断网以后检查插头 is understandable, but its naturalness depends on the context.

It could be either, depending on context.

Because Chinese often omits subjects, 断网以后 can be interpreted as:

1. after you disconnect the network
2. after the network is disconnected
3. after the network goes down

In a step-by-step instruction, people will usually understand it as something like:

• after disconnecting the network

But without more context, the phrase itself can be slightly ambiguous.

If someone wanted to be more explicit, they might say:

• 断开网络以后…… = after disconnecting the network...
• 网络中断以后…… = after the network is interrupted...

Because this is not talking about a completed past event in a narrative. It is giving an instruction or stating a sequence.

Chinese often leaves out 了 in:

• commands
• instructions
• general procedures

So:

• 断网以后检查插头。
  feels like After disconnecting the network, check the plug.

If you added 了, the sentence would shift more toward describing something that has already happened, or marking completion more explicitly. For example:

• 断网以后，检查了插头。
  This sounds more like After the network was disconnected, the plug was checked.

That is a different kind of sentence.

It is a simple verb + object structure:

• 检查 = to inspect / check
• 插头 = plug
• 检查插头 = check the plug

This is one of the most common Chinese sentence patterns:

• 看书 = read a book / read books
• 洗手 = wash hands
• 检查设备 = inspect the equipment
• 检查插头 = inspect the plug

So grammatically, there is nothing unusual here.

These are easy to confuse.

• 插头 = plug
  The part attached to a cord that you insert into something.
• 插座 = socket / outlet
  The wall outlet or power strip outlet.
• 插口 = port / jack / socket opening
  A more general word for an opening where something is inserted.

Examples:

• 把插头拔出来。
  Pull out the plug.
• 插座坏了。
  The outlet is broken.
• 耳机插口在哪里？
  Where is the headphone jack?

So in your sentence, 插头 specifically means the plug, not the wall outlet.

Chinese usually does not use articles like a, an, or the.

So 插头 can mean:

• a plug
• the plug
• plugs

The exact meaning depends on context.

In a sentence like this, 检查插头 is naturally understood as check the plug or check the plug(s) that are relevant in the situation.

This is very normal in Chinese. For example:

• 关门。
  could mean Close the door.
• 打开窗户。
  could mean Open the window.

Chinese relies much more on context than English does for this.

Yes. That is very natural.

后 is a shorter form here, and 断网后检查插头 means the same thing as 断网以后检查插头.

In many written instructions, 后 sounds a little more compact and concise:

• 重启后再试。
  Try again after restarting.
• 连接后检查设置。
  Check the settings after connecting.

So both are fine:

• 断网以后检查插头
• 断网后检查插头

The version with 以后 can feel a bit fuller; the version with 后 is often more compact.

Yes, you could use 之后 here:

• 断网之后检查插头。

Both 以后 and 之后 can mean after.

In many everyday sentences, they are very similar. The difference is often more about style than meaning:

• 以后 is very common and versatile
• 之后 can feel slightly more formal or written in some contexts

For this sentence, both work.

Examples:

• 下班以后回家。
• 下班之后回家。

Both mean:

• Go home after work.

Yes, often it would.

Chinese frequently uses 先 and 再 to make the sequence especially clear:

• 先断网，再检查插头。
  First disconnect the network, then check the plug.

This often sounds very natural in spoken instructions because it clearly marks the order.

Compared with that:

• 断网以后检查插头。

is still correct, but it is a little more compact and matter-of-fact.

Both patterns are common:

• 先 X，再 Y
• X 以后 Y

Yes, and that often sounds more natural in everyday speech.

• 检查插头 = direct, plain, instructional
• 检查一下插头 = a bit softer, lighter, more conversational

一下 does not literally mean one time here. Very often it softens the action.

So you might hear:

• 断网以后检查一下插头。

That sounds like:

• After disconnecting the network, take a look at the plug.

In a manual or warning label, the shorter 检查插头 is very normal. In conversation, 检查一下插头 often feels smoother.

It leans a bit toward instructional written Chinese, though it could also be spoken.

Why?

• It is short.
• The subject is omitted.
• The verbs are direct.
• It sounds like a procedural step.

This style is common in:

• manuals
• troubleshooting guides
• safety notices
• step-by-step instructions

In more natural spoken Chinese, someone might say:

• 先断网，再检查一下插头。
• 断网以后，你检查一下插头。

These feel a little more conversational because they include sequencing words or a subject.