Cabling choices in walls. Your experience and advice.

Hello.

I'm new to networking and I look for your experience and advice in this topic. I started to work in local school about mid october last year. Before that I worked in different school, but whit very basic and minimal network. At current work place we have more complex and larger network whit 23 APs, multiple switches, proper server racks etc. All is fresh, school was under renovation and was completed two years ago.

After inspecting network I noticed quite a lot issues whit it, in my opinion atleast. This time I will ask only about one - is it wise to use cat5e and cat6, both unshielded (utp) in walls? They are all mushed together and they all go paralel big ventilation pipes, electric wiring and god knows what else in walls and around them. Far as I know, in this situation shielded wiring is more appropriate choice as internet in school is important and user count on network reaches 550-600 devices daily, most of them are wireless.

What is your experiance? Does shielded wiring in this situation matter that much? I have tested network and I have noticed packet drops and speed drops in network while testing whit iperf3, that can be caused by this. iperf3 server and client was on wired connection at both ends. I want to know this for my own knowledge, so I don't make mistakes when I need to do something like this.