Learn Hardcore German: Am Bahnhof verpasse ich manchmal den Anschlusszug, wenn mein Bus zu spät kommt. - At the train station I sometimes miss the connecting train when my bus is late.

In your sentence, we’re talking about catching a connecting train in general, so am Bahnhof (in the area of the station, not specifically inside the building) is more natural. If you specifically meant inside the hall/building, you could say im Bahnhof.

Why does the sentence start with Am Bahnhof and then put the verb verpasse before ich?

German main clauses follow the verb-second (V2) rule: the conjugated verb must be in the second position of the sentence.

Positions here are counted by chunks, not individual words.

Am Bahnhof → first position (a prepositional phrase)
verpasse → second position (the verb)
ich manchmal den Anschlusszug → the rest

You could also say:

Ich verpasse am Bahnhof manchmal den Anschlusszug, …

Here:

Ich → first
verpasse → second

Both are grammatically correct. Putting Am Bahnhof first just emphasizes the location.

Why is it den Anschlusszug and not der Anschlusszug?

Anschlusszug is masculine:

nominative: der Anschlusszug
accusative: den Anschlusszug

In this sentence, den Anschlusszug is the direct object of verpasse (I miss what? → the connecting train), so you need the accusative case.

That’s why it’s den instead of der:

Ich verpasse den Anschlusszug. ✔
Ich verpasse der Anschlusszug. ✘ (wrong case)

What exactly does Anschlusszug mean, and is it always one word?

Anschlusszug is a compound noun:

der Anschluss = connection
der Zug = train
→ der Anschlusszug = connecting train

In German, compounds are usually written as one word, not separately:

Anschluss + Zug → Anschlusszug (correct)
Anschluss-Zug (hyphen) – only in special typography cases
Anschluss Zug (two words) – wrong

So you should always write Anschlusszug as one word in normal usage.

Why is the verb kommt at the end in wenn mein Bus zu spät kommt?

Wenn introduces a subordinate clause (Nebensatz) in German.
In subordinate clauses, the conjugated verb goes to the end of the clause.

Structure:

wenn (subordinating conjunction)
mein Bus (subject)
zu spät (adverbial)
kommt (verb at the end)

So:

…, wenn mein Bus zu spät kommt.

If you started with this clause, the main clause verb would move to second position in the main clause that follows:

Wenn mein Bus zu spät kommt, verpasse ich manchmal den Anschlusszug.

Why is wenn used here instead of wann or als?

wenn, wann, and als all relate to time, but they are not interchangeable:

wenn
- for repeated/general events: whenever/when(ever)
- also used like if (conditional)
- Works in present, past, future
- Example: Wenn mein Bus zu spät kommt, verpasse ich den Anschlusszug.
  → Whenever / If my bus is late, I miss the connection.
wann
- means when? as a question word (direct or indirect questions)
- Example: Wann kommt der Bus? / Ich weiß nicht, wann der Bus kommt.
als
- only for a single event in the past
- Example: Als mein Bus gestern zu spät kam, habe ich den Anschlusszug verpasst.

In your sentence, we describe something that can happen repeatedly in general, so wenn is correct.

Where can manchmal go in this sentence? Is verpasse ich manchmal the only correct order?

Manchmal is an adverb of frequency (like sometimes), and German allows some flexibility. All of these are correct, with slightly different emphasis:

Am Bahnhof verpasse ich manchmal den Anschlusszug, …
(neutral; very natural)
Ich verpasse am Bahnhof manchmal den Anschlusszug, …
(also very natural)
Ich verpasse manchmal am Bahnhof den Anschlusszug, …
(focus slightly more on sometimes at the station as opposed to elsewhere)

Less typical or marked:

Manchmal verpasse ich am Bahnhof den Anschlusszug, …
(emphasizes sometimes by putting it first)

The main rules:

In a main clause, the conjugated verb must stay in second position.
Manchmal usually sits somewhere in the “middle field” (between subject and main object, or close to the verb).

Could I say weil mein Bus zu spät kommt instead of wenn mein Bus zu spät kommt? What’s the difference?

You can say:

…, weil mein Bus zu spät kommt.
= … because my bus is late.

Difference in nuance:

wenn → whenever / if / when
- General condition or repeated situation.
- Focus on the condition: under this circumstance, I miss the train.
weil → because
- A cause/reason.
- Focus on why you miss the train.

Your original sentence with wenn describes a general pattern/condition.
With weil, you would be explicitly explaining the reason.

Why is the tense just simple present (verpasse, kommt) and not a future tense like werde verpassen?

German uses the present tense much more than English, even for:

general statements
repeated actions
scheduled future events

Am Bahnhof verpasse ich manchmal den Anschlusszug, wenn mein Bus zu spät kommt.

can mean:

I sometimes miss the connecting train (as a regular occurrence)
I sometimes will miss it when this situation arises (future in a general sense)

A future tense (with werden) is only needed when:

the timing really must be highlighted as future, or
there could be confusion with a present meaning

Here, present tense is natural and idiomatic.

What does zu spät literally mean, and why isn’t it kommt zu spät instead of zu spät kommt?

Zu spät literally means too late or late.

zu here = too (in the sense of "excessively")
spät = late

In a normal main clause, the order would be:

Der Bus kommt zu spät. (The bus is/comes too late.)

But in a subordinate clause, the verb goes to the end:

main clause: Der Bus kommt zu spät.
subordinate clause: …, weil der Bus zu spät kommt.
→ zu spät kommt, not kommt zu spät, because of the verb-final rule.

Why is it mein Bus and not meinen Bus or meinem Bus?

Bus here is the subject of the subordinate clause:

wer oder was kommt zu spät? → mein Bus (who/what is late?)

The subject in German is in the nominative case.

Declension of mein with masculine der Bus:

nominative: mein Bus (subject)
accusative: meinen Bus
dative: meinem Bus

So nominative mein Bus is correct here:

wenn mein Bus zu spät kommt ✔ (subject)
wenn meinen Bus zu spät kommt ✘
wenn meinem Bus zu spät kommt ✘

Does verpassen split like other German verbs (e.g., anrufen → ich rufe an)?

No. Verpassen is not a separable verb; it’s inseparable.

ver- is an inseparable prefix, so the verb always stays in one piece:
- ich verpasse
- ich habe verpasst
- ich würde verpassen

You never say:

ich passe ver ✘

Compare:

separable: anrufen → ich rufe dich an
inseparable: verpassen → ich verpasse den Zug

Is there any special reason manchmal is in the main clause and not in the wenn-clause?

Yes, it affects what is being described as “sometimes”:

Am Bahnhof verpasse ich manchmal den Anschlusszug, wenn mein Bus zu spät kommt.
→ Sometimes I miss the connecting train (whenever my bus is late).
The condition (“when my bus is late”) is general; the result happens sometimes.

If you move manchmal into the wenn-clause:

Am Bahnhof verpasse ich den Anschlusszug, wenn mein Bus manchmal zu spät kommt.
→ I miss the connecting train whenever my bus is sometimes late.
This sounds odd: a bus is either late on that specific occasion or not; “is sometimes late” doesn’t fit well inside a single wenn-clause trigger.

So it’s more natural to keep manchmal with the main action (verpasse ich …).