I recently just got my self an XR500, and just got it all setup and running, It was originally on outdated firmware when I got the router and told me it wanted to auto-update, so I let it (During setup)
After all the setup stuff I got it all done and was happy with it. I don't currently use any of the QoS or Geo-filter features as I'm not much of a console person, but I do host in home game servers. So I do have ports open.
I later on downgraded to version 22.214.171.124 because I was having stability issues, the router would randomly drop all wired connections (and only wired) wireless would be fine, so I downgraded thinking that it would fix my issue, So far it dose but now I have a new problem.
I have noticed is that randomly... totally randomly the CPU usage on the router will spike to 100% usage, making all parts of the internet and all my game server lag out and disconnect. There is nothing in the Logs of the router that I see to suggest its attempting to block something or do something that would result in this, but it just randomly spikes to 100% and holds at 100%... During that time the router becomes almost totally unusable... Pinging anything even locally on my network because unstable and heavily delayed or impossible, normal internet usage becomes impossible on wired and wireless... I'm unsure of what to do to solve this, I downgraded to 126.96.36.199 because from all the other posts on this forum people said its very stable, I don't use any of the features that everyone always asks about (Such as QoS or Geo-filter). I have a static IP setup so its not anything to do with DHCP, I honestly don't know what to do. On normal usage (Me on Ethernet and people on wifi) the router sits at about 20% cpu usage.