Help! Unknown Maxlinear Device is detected everywhere except by Virgin router and app

Hello, I would be grateful for any asistance in figuring out what ion earth s going on with my WIFI. Please keep  in mind that my knowledge on computer is basic . I had a new router recently (hub 3)  from Virgin . I set up my router with my own password and new network name. Also my router was set to 4Ghz only initially.The first few days everything was fine. Only my connected devices were recognised by both the router settings and my computer, virus scanner, fing etc... Then one night the router rebooted itself and once it was back on there were two main differences . One was that connection was now both 4GHz and 5G then a new device showed up on my network when doing look up on my laptop, Fing,  Virus scanner. Unknow Device as a brand of Maxlinear with Mac address: **:**:**:**:**:** and IP address : 192.168.0.100 . This device was not detected at all before that reboot and nothing changed in my house set up. My router and virgin media app do not detect such device,  however, still tried to filter the Mac address but it still shows up online. I called Virgin media about it and they tried to reassure me that on their side they could not see the device so it should be all good but this is not much reassurance, especially that I know that none of those agents are IT experts so I could have a ghost device spying on my every move without knowing and they wouldn't know about it.  I really would like to have reassurance as to exactly what the hell this random device is. Its frustrating seeing it popping up not knowing what it is. Could it be due to the 4ghz/5g change ? Can it be an element of the router that somehow is detected as a difference device outside of the router settings ? Is it something I can relax about or should I be worried?  Only suspicious thing that happened so far was that I received an email from Disney plus about a new log in from my actual location  but from an email that is NOT linked to my Disney plus account so not sure if it's a coincidence or if it's due to that random device. If someone can direct  me towards an easy guide to follow about how to kick out unknown device that are not detected by router , I would appreciate or even if someone could give me an idea as to what that device could be or if it is harmless or not. Everything online is about stopping devices that a&e recognised by the router settings but there are very little info about when there is a device only detected externally.  Thank you so much in advance. I really need a peace of mind about this.