Cloud Network Technology (Samoa) Limited device on my wifi?

[wireless]

Cloud Network Technology (Samoa) Limited

Can someone please help me out to identify what this device is and why it continues to connect and disconnect from my home WiFi throughout the day and night. I know that when my ex has shown up it has connected minutes after his iPhone connects to our WiFi. He did used to live here and does know the WiFi passwords and has had access to our Ethernet and router... and also has a history of hacking and using "backdoor" to hack into my accounts and get information. He has know said somethings that are very concerning regarding my bank account activity and also deposits i have received in my account etc.. I will attach my system log to show the activity and how often it has logged on and off and even doing so when he is not around but is at work and i am the only one at the house and know all of the devices that are connected to our WiFi. I may be completely paranoid but given that he has now shared information about my finances, I do feel uneasy doing anything online anymore..
I colored in pink where the device has connected and disconnected, just a few of the times and there are a lot more throughout just today..
28:3a:4d:b8:bd:4d is the mac of what comes up under Cloud Network Tech (Samoa) ?

I am just looking for clarity as I have searched the mac and also have written down all devices that connect to our WiFi. Including our security cameras, WiFi booster from Telus, PS4 and so on.. and this does not link up to anything we have in our home...

Please help.. Thank you




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