No quiero frustrarme si el wifi sigue fallando.

Because Spanish often uses the reflexive form to express becoming an emotional state.

• frustrar = to frustrate someone/something
• frustrarse = to get frustrated / become frustrated

So No quiero frustrarme means I don’t want to get frustrated.

Literally, it looks like to frustrate myself, but in natural English it is usually just to get frustrated.

Because after a conjugated verb like quiero, Spanish can attach a pronoun to the infinitive.

• No quiero frustrarme
• No me quiero frustrar

Both are correct and mean the same thing.

This is very common with verbs like querer, poder, deber, ir a, etc.

Examples:

• Quiero acostarme
• Me quiero acostar

Because the subject is the same for both verbs.

• quiero = I want
• frustrarme = to get frustrated

The person who wants and the person who would get frustrated are both I, so Spanish uses:

• querer + infinitive

If the subject changes, Spanish usually uses que + subjunctive instead:

• Quiero descansar = I want to rest.
• Quiero que descanses = I want you to rest.

seguir + gerundio means to keep doing something or to continue doing something.

So:

• sigue = continues / keeps
• fallando = failing / malfunctioning

Together, sigue fallando means:

• keeps failing
• continues to malfunction
• is still not working properly

With wifi, fallar usually means the connection is unreliable, cutting out, or not working properly.

Using seguir + gerundio emphasizes an ongoing or repeated problem.

• si el wifi falla = if the wifi fails / if the wifi doesn’t work
• si el wifi sigue fallando = if the wifi keeps failing / continues not to work

So sigue fallando suggests this is not a one-time issue. It has already been happening and is continuing.

Because si without an accent means if.

• si = if
• sí = yes

So in this sentence:

• si el wifi sigue fallando = if the wifi keeps failing

This is a very common spelling point in Spanish.

Because this sentence describes a real or possible condition, so Spanish uses the indicative:

• si el wifi sigue fallando

That is the normal pattern for real conditions in the present.

Compare:

• Si el wifi sigue fallando, me voy.
  If the wifi keeps failing, I’m leaving.

But for a more hypothetical or unlikely idea, Spanish often uses the imperfect subjunctive:

• Si el wifi siguiera fallando, me frustraría.
  If the wifi kept failing / were to keep failing, I would get frustrated.

So in your sentence, the present indicative is the correct choice.

In Spain, wifi is very commonly treated as masculine:

• el wifi

So el wifi sigue fallando is completely natural.

You may occasionally hear variation, but el wifi is the standard choice for most learners to use.

Yes, but in everyday Spanish it often means to malfunction, to not work properly, or to let someone down.

With technology:

• El ordenador falla = The computer is malfunctioning.
• La conexión falla = The connection is acting up.
• El wifi sigue fallando = The wifi keeps failing / keeps malfunctioning.

So here fallar is more about unreliable performance than about failure in an abstract sense.

Yes. That is also correct.

Both are natural:

• No quiero frustrarme si el wifi sigue fallando
• No me quiero frustrar si el wifi sigue fallando

The meaning is the same. The difference is mainly where the reflexive pronoun goes.

Learners often find No quiero frustrarme slightly easier to process because the pronoun stays attached to the infinitive, but both are standard.

Frustrarme is a very good and natural choice.

But depending on the emotion you want, Spanish could also use:

• enfadarme = to get angry
• desesperarme = to get desperate / fed up
• molestarme = to get annoyed

So:

• No quiero frustrarme = I don’t want to get frustrated.
• No quiero desesperarme = I don’t want to get too stressed/fed up.

In your sentence, frustrarme works very well because it matches the idea of repeated technical problems causing frustration.