Learn Hardcore German: Ich verpasse den Anschluss.

verpassen – to miss an event/chance/connection:
- Ich verpasse den Anschluss. = I miss the connection.
- Ich habe die Sendung verpasst. = I missed the show.
vermissen – to miss someone/something emotionally:
- Ich vermisse dich. = I miss you (emotionally).
verlieren – to lose (an object, a game, etc.):
- Ich verliere meinen Schlüssel. = I lose my key.

So for a train/bus/flight connection, you need verpassen, not vermissen or verlieren.

Why is it den Anschluss and not der Anschluss?

Der Anschluss is the basic (nominative) form:

Der Anschluss ist wichtig. = The connection is important.

In Ich verpasse den Anschluss, den Anschluss is the direct object of the verb verpassen, so it must be in the accusative case.

For masculine nouns with the article der, the accusative form is den:

Nominative: der Anschluss
Accusative: den Anschluss

So den Anschluss is required here because it is what you are missing.

What gender is Anschluss, and how does it decline?

Anschluss is masculine: der Anschluss.

Its singular forms:

Nominative: der Anschluss
Accusative: den Anschluss
Dative: dem Anschluss
Genitive: des Anschlusses

Plural:

Nominative: die Anschlüsse
Accusative: die Anschlüsse
Dative: den Anschlüssen
Genitive: der Anschlüsse

In your sentence you only need the masculine accusative singular: den Anschluss.

Can Ich verpasse den Anschluss refer to the future, or is it only present?

Grammatically it’s present tense, I am missing the connection.

However, German present tense is very often used for near or planned future events, especially with timetables and arrangements. So in context, Ich verpasse den Anschluss usually means:

I’m going to miss my connection / I will miss my connection, often because you already know your current train is late.

If you want to make the future extra explicit, you can say:

Ich werde den Anschluss verpassen. = I will miss the connection.

How would I say I missed the connection (past tense) in German?

Most commonly in spoken German you use the Perfekt (present perfect):

Ich habe den Anschluss verpasst. = I missed the connection.

In more formal/written style you might see the Präteritum (simple past):

Ich verpasste den Anschluss.

Both are correct; Ich habe den Anschluss verpasst is what you’ll normally say in conversation.

Is verpassen a separable verb? Where does the prefix go in other tenses?

verpassen is not separable. The prefix ver- is an inseparable prefix in German.

That means:

Present: ich verpasse, du verpasst, er verpasst
Perfect: ich habe verpasst (no extra ge- in the middle)
There is never a form like ich passe … ver.

Examples:

Ich verpasse den Anschluss.
Ich habe den Anschluss verpasst.
Ich werde den Anschluss verpassen.

Does Anschluss only mean a train/bus connection, or can it be used in other ways?

Anschluss has several meanings; in your sentence, it’s a transport connection (between trains, buses, flights).

Other common uses:

Telefonanschluss – telephone line/connection
Internetanschluss – internet connection
Anschluss an etwas finden – to become integrated/join in / get connected socially
den Anschluss verlieren – to fall behind (technologically, socially, etc.)

So Ich verpasse den Anschluss literally means missing a transport connection, but similar phrases with Anschluss can be used metaphorically as well.

What is the difference between Anschluss and Verbindung when talking about trains or buses?

Both can relate to transport, but they’re used a bit differently:

der Anschluss
Usually: the connecting train/bus/flight after another one.
- Ich habe nur 5 Minuten für den Anschluss. = I only have 5 minutes to catch my connection.
die Verbindung
More general: the connection / route / service from A to B.
- Gibt es eine direkte Verbindung nach Berlin? = Is there a direct connection to Berlin?

In Ich verpasse den Anschluss, you’re clearly talking about a connecting service, not just any connection.

Could I say Ich vermisse den Anschluss instead?

No, that would be wrong in this context.

Ich verpasse den Anschluss. = I miss (fail to catch) the connection.
Ich vermisse den Anschluss. would mean something like I miss the connection (emotionally), which doesn’t make sense for a train/bus connection.

vermissen is for emotional missing:

Ich vermisse meine Freunde. = I miss my friends.

For missing a train/connection/event, you need verpassen.

How do I pronounce Ich verpasse den Anschluss correctly?

Key points:

Ich – the ch is the soft ich-sound [ç], not like English k:
- Say something like ish but with the tongue closer to the palate, more hissing than sh.
verpasse – stress on the second syllable: ver-PAS-se.
den – like English “den” in “denim” (but shorter).
Anschluss – stress on An: AN-schluss.
- sch is like English sh,
- ss is a short, sharp s.

Rough phonetic guide:
[ɪç fɛɐ̯ˈpasə deːn ˈanʃlʊs]

Can I replace den Anschluss with a pronoun? How would the word order change?

Yes. If the connection has already been mentioned, you can use ihn (masculine accusative pronoun):

Ich verpasse ihn. = I’m going to miss it (the connection).

In a longer sentence with more elements, pronouns tend to move earlier:

Wegen der Verspätung verpasse ich ihn.
(Because of the delay, I will miss it.)

But the basic structure with a single verb is:

Subj. – Verb – (object)
→ Ich verpasse ihn.

How would I use this idea in a longer sentence with a wenn-clause (if/when)?

In a wenn-clause, the conjugated verb goes to the end of that clause, and in the main clause it’s in normal second position:

Wenn der Zug zu spät ankommt, verpasse ich den Anschluss.
= If/When the train arrives too late, I (will) miss the connection.

Structure:

Wenn
- [subject + … + verb at end], [subject + verb in 2nd position
  - …].

You could also flip the order:

Ich verpasse den Anschluss, wenn der Zug zu spät ankommt.