I don't want to bury the lead. For security reasons, Microsoft may not allow older processors to connect to their Playfab service because they are vulnerable to certain classes of side-channel exploits. All Intel CPUs up to I think the 9th gen, and all ryzen through the 2000 series are vulnerable to this side channel attack, and did not have access to the mitigations deployed for them. Intel 10th Gen and beyond and Ryzen 3000, 5000 and 7000 are fine, unless I'm misremembering what generations were affected.

That's just a hypothesis of course.