We are going from 10 to 25 people this year. What breaks first?

Growth breaks things in a predictable sequence, and knowing the sequence lets you get ahead of it rather than reacting.

• Wi-Fi goes first. The single access point that covered ten people will not cover twenty-five, and the failure is gradual and confusing rather than obvious. It gets slow in the afternoon, people drop off calls, and everyone blames the internet. Access point capacity is about concurrent devices as much as coverage, and at twenty-five people you are carrying sixty or seventy devices once phones are counted.
• File permissions, second. At ten people everyone can see everything and it is fine. At twenty-five it is not fine, and by then the folder structure has grown organically and untangling it is a project. Doing it at fifteen is an afternoon. Doing it at forty is a month.
• The informal support model, third and hardest. The office manager or the one technical person who has been handling IT alongside their actual job hits a wall. It is rarely announced. It shows up as that person being unavailable for their real work, and as small problems going unfixed for weeks because nobody has time.
• Onboarding, fourth. Setting up a new person by hand is fine twice a year. At the pace of hiring fifteen people, doing it by hand means inconsistent setups, accounts with wrong access, and new hires sitting idle on day one.

Two more that arrive quietly: your internet circuit, which was adequate at ten and is a bottleneck at twenty-five, particularly for uploads; and your phone system, if it is a box in the closet with a fixed number of lines.

The cheap move is to handle Wi-Fi and file structure before you hire rather than after. Both are much easier when there are fewer people to disrupt and fewer files to sort.