Serious Discussion What a hacker can do on the same network (LAN)?

[Azazel]

Supposed it's not a public wifi or open network but a caffe or hotel network (password protected - encrypted).
Can they still sniff your traffic and perform man-in-the-middle attacks or are they left only with port scanning and potential exploits to access your device?

Edit:
Not Home specifically

 

[Zorro]

Yes. Firstly, the simplest thing they can do is use your Internet for free (especially high-speed and unlimited). Secondly, they can hack the router and through this control all your traffic, slip their phishing or fraudulent sites, hack your social media accounts and ask your friends for money on your behalf, write insults. And also, which is especially scary, they can hack bank accounts and issue loans on your behalf, and if you use the services of some government web services where you need to provide personal data (passport, insurance data, etc.), then they can, without your consent, carry out transactions with your property using this data.
Then you will have to prove in court that you did not take out loans from the bank, did not sell your house to someone, and so on, and you will have to explain to your friends that it was not you who wrote insults to them, did not ask them to borrow money.
In general, attackers can do a lot of things by penetrating your Wi-Fi network.

 

[RoboMan]

Once in the same LAN, a cybercriminal can see all connected devices as long as they're not hidden. In the IoT era, this means lots of devices, such as personal computers, smartphones, smart TVs, anything connected to the internet. All those devices can be accessed by the intruder if the password is weak and/or are not properly protected by firewall rules.

But remember, nowadays it's not necessary to hack computers, it's easier to hack people.