من الأفضل أن تتصل بالدعم الفني.

It means it is better or it would be better.

In this sentence, من الأفضل أن... is a very common Arabic pattern for giving advice in a polite, indirect way. A natural English translation is:

It would be better to contact technical support.
or simply
You should contact technical support.

So even though the wording is not identical to English, the function is the same: it gives a recommendation.

أن is used to introduce a verb phrase after expressions like من الأفضل.

So:

• من الأفضل = it is better
• أن تتصل = that you contact / to contact

In natural English, we often translate أن + present verb here as an infinitive:

• من الأفضل أن تتصل = it is better to contact

So أن is doing the job of linking the recommendation to the action.

Because Arabic verbs usually include the subject inside the verb itself.

تتصل already tells you:

• the subject is you
• it is singular
• and in this form it is masculine

So Arabic does not need a separate أنت unless you want emphasis.

That is why the sentence does not say أنت تتصل. The you is already built into تتصل.

Yes. In this sentence, تتصل is addressing one male.

Here are the main versions:

• to one man: من الأفضل أن تتصل بالدعم الفني.
• to one woman: من الأفضل أن تتصلي بالدعم الفني.
• to a group of men or a mixed group: من الأفضل أن تتصلوا بالدعم الفني.
• to a group of women: من الأفضل أن تتصلن بالدعم الفني.

So the sentence you were given is the masculine singular version.

تتصل comes from the verb اتصل بـ and means you contact, you get in touch with, or sometimes you call.

In this sentence, the most natural meaning is contact or get in touch with:

• تتصل بالدعم الفني = contact technical support

Depending on context, it can also imply a phone call, but it does not have to. It is broader than just phone.

Because the verb اتصل normally takes the preposition بـ.

So in Arabic, you do not usually say اتصل الدعم. You say:

• اتصل بالدعم = contact the support / get in touch with the support

So the بـ is required by the verb.

A literal sense is something like get in touch with.

Because adjectives normally come after the noun in Arabic.

So:

• الدعم = the support
• الفني = technical

Together:

• الدعم الفني = technical support

This is the normal Arabic word order for noun + adjective.

Also, the adjective must match the noun in things like definiteness. Since الدعم has الـ, the adjective also has الـ:

• الدعم الفني not
• الدعم فني

Because Arabic adjectives agree with the nouns they describe in definiteness.

So if the noun is definite:

• الدعم = the support

then the adjective must also be definite:

• الفني = the technical

Together they mean:

• الدعم الفني = the technical support

This is a very important rule in Arabic: noun and adjective usually match in:

• definiteness
• gender
• number
• case

If fully vowelled, the sentence is:

مِنَ الأَفْضَلِ أَنْ تَتَّصِلَ بِالدَّعْمِ الفَنِّيِّ

A few things are happening:

• الأفضلِ is after من, so it is in the genitive
• تتصلَ is after أن, so it is in the subjunctive
• الدعمِ is after the preposition بـ, so it is in the genitive
• الفنيِّ matches الدعمِ, so it is also genitive

In normal unvowelled Arabic writing, these endings are usually not shown, which is why learners often do not notice them at first.

Because in unvowelled Arabic script, the change is often invisible.

Without full vowels, you see:

• تتصل

But with full vowels:

• indicative: تَتَّصِلُ
• subjunctive after أن: تَتَّصِلَ

So the final short vowel changes from u to a, but that is usually not written in ordinary Arabic text.

This is very common in Arabic: the grammar changes, but the spelling may look the same unless vowel marks are added.

No. It is usually advice or a recommendation, not a direct command.

Compare:

• من الأفضل أن تتصل بالدعم الفني. = It would be better to contact technical support.
• يجب أن تتصل بالدعم الفني. = You must contact technical support.

So من الأفضل أن sounds softer and more polite than يجب أن.

In بالدعم, the ل of الـ is not pronounced clearly because د is a sun letter.

So:

• written: بالدعم
• pronounced roughly: bid-daʿm

The l of الـ assimilates to the d sound.

But in الفني, the ف is a moon letter, so the l is pronounced:

• al-fannī

So the whole phrase is pronounced approximately:

min al-afḍal an tattasil bid-daʿm al-fannī

Yes. That is also correct.

Compare:

• من الأفضل أن تتصل بالدعم الفني = It is better that you contact technical support
• من الأفضل الاتصال بالدعم الفني = It is better to contact technical support

The version with أن + verb sounds a bit more directly tied to you.
The version with the verbal noun الاتصال is a little more neutral or impersonal.

Both are very normal Arabic.