man in the middle – Have I just experienced a MitM attack or is my ISP updating my hardware without my permission?

I was casually surfing the web when suddenly the antivirus on my laptop started warning on supposed ARP Spoofing attacks coming from my router’s IP, which got blocked.

The internet on my phone continued to work completely fine, but on my laptop after the blocking occurred all packets sent to IPv4 addresses got timed out. What has happened here? The internet is fine now on IPv4 and IPv6.

Maybe I’m just paranoid and the ISP was somehow doing maintenance or something like that?

P.S. I could only access the router thru the DNS name and not the IPv4 IP address for some reason too…

I am using ESET Internet Security AV solution.