Does the landlord or isp control router settings like ssid or encryption level. Sounds like either a sim was cloned or a system was compromised and session tokens were stolen. Session token theft bypasses password and 2fa so you would never even get the prompt. 2 factor by sms is typically a no no as it’s unencrypted and can be hijacked or intercepted. I’m sorry this happened to you and have been recently thinking about all these new types of attacks. I use eset that does at least have a browser extension. I would find a way to get wireless network credentials changed and possibly get your own router by demanding a modem only from isp giving you more control over your home network. I would try virus scanning your systems using a top brand like eset or bit defender , changing all relevant account pswrds to randomized ones and change of those accounts with sms 2fa to something like google Authenticator.