@MRCUR wrote: @Mosquitar wrote: Hi,   Did you ever get this issue resolved? If so, what was the fix as we are experiencing issues with a topology similar to yours.   Thanks Unfortunately not. I had to reopen the support case today as the issue (likely with DNS) is still occurring and causing instability for the 425 stack. The school year ended before we were able to determine a root cause last year so hopefully it can be found this time around.  The remaining issue is being caused by malformed DNS packets through the app X-VPN - https://xvpn.io/. The individual packets are significantly larger than would be expected for a DNS response and are possibly all being sent to the MS425 CPU to process for DNS inspection.    We've put in place ACL's on the 425 stack temporarily to block all DNS traffic that does not go to or come from our internal DNS servers. MS engineering is looking into the issue.  ... View more