Mieliśmy zrobić aktualizację systemu, ale w biurze nie było zasięgu.

Not literally. In this sentence, mieć + infinitive means something like:

• we were supposed to do
• we were to do
• we had planned to do

So Mieliśmy zrobić aktualizację systemu means We were supposed to do / We had planned to do a system update.

Grammatically, mieliśmy is the past tense of mieć (to have), but in this pattern it expresses obligation, arrangement, or intention rather than possession.

Mieliśmy is:

• past tense
• 1st person plural
• masculine-personal or mixed-gender group

It comes from mieć (to have).

So:

• miałem = I had / I was supposed to
• miałeś = you had / you were supposed to
• mieliśmy = we had / we were supposed to

Because Polish usually drops subject pronouns, my (we) is not needed. The ending -śmy already tells you it means we.

Because zrobić is the perfective form, and here it suggests a completed action: doing the update as a single finished task.

• robić = imperfective, ongoing/repeated/general doing
• zrobić = perfective, to do and complete

So:

• Mieliśmy robić aktualizację systemu would sound more like we were supposed to be doing / to work on a system update
• Mieliśmy zrobić aktualizację systemu means we were supposed to carry out and complete the update

For a one-time task with a clear result, zrobić is very natural.

Aktualizację is accusative singular, because it is the direct object of zrobić.

Base form:

• aktualizacja = update

Accusative singular:

• aktualizację

Then systemu is genitive singular, because Polish often uses the genitive for the second noun in a noun + noun phrase like update of the system.

So:

• aktualizacja systemu = system update / literally update of the system
• zrobić aktualizację systemu = to do/carry out a system update

After w meaning in, Polish uses the locative case.

Base form:

• biuro = office

Locative singular:

• w biurze = in the office

So:

• w biurze = in the office

You would not use biuro here because that is nominative/accusative, not locative.

Because the phrase is nie było zasięgu = there was no signal/reception.

Polish often uses było in impersonal existence statements, similar to English there was.

Here:

• było = neuter singular past form of być (to be)
• nie było = there was not / there wasn’t

This structure is very common:

• Nie było czasu = There was no time
• Nie było problemu = There was no problem
• Nie było zasięgu = There was no signal

So it is not really agreeing with a specific normal subject in the same way as on był / ona była.

Because after a negated existential expression like nie było (there wasn’t), Polish uses the genitive.

Base form:

• zasięg = signal / range / reception / coverage

Genitive singular:

• zasięgu

So:

• był zasięg = there was signal
• nie było zasięgu = there was no signal

This genitive after negation is a very common pattern in Polish.

Here zasięg means signal, reception, or coverage, usually for a phone or mobile network.

So w biurze nie było zasięgu means:

• there was no signal in the office
• there was no reception in the office
• there was no coverage in the office

In other contexts, zasięg can also mean range more generally.

Because Polish often leaves out subject pronouns when the verb ending already makes the subject clear.

In mieliśmy, the ending tells us the subject is we.

So:

• (My) mieliśmy zrobić aktualizację systemu = We were supposed to do a system update
• Mieliśmy zrobić aktualizację systemu = same meaning, and this is the more natural neutral version

Polish usually includes pronouns like my only for emphasis or contrast.

Yes. Polish word order is more flexible than English, although the original sentence is very natural.

Original:

• Mieliśmy zrobić aktualizację systemu, ale w biurze nie było zasięgu.

You could also say:

• W biurze nie było zasięgu, ale mieliśmy zrobić aktualizację systemu.

That changes the emphasis, not the basic meaning. The original version starts with the plan/task and then explains the problem.

Ale means but.

It connects the two parts of the sentence:

• Mieliśmy zrobić aktualizację systemu = We were supposed to do a system update
• ale w biurze nie było zasięgu = but there was no signal in the office

So ale introduces the obstacle or contrast: there was a plan, but something prevented it.

Yes, that is the natural implication.

The first part says there was an intention or obligation:

• Mieliśmy zrobić aktualizację systemu = We were supposed to do the update

The second part gives the reason it likely did not happen:

• ale w biurze nie było zasięgu = but there was no signal in the office

So together, the sentence strongly suggests: we planned to do it, but we couldn’t.