Windows 11 24H2+ - Dismal SMB performance with 3rd Party Storage

Ever since we have upgraded our machines to 24H2 and 25H2 respectively, we've been seeing very poor SMB performance while reading, saving and copying to both of our Isilon storage clusters when over the WAN. LAN transfers are probably affected, but masked due to low latency. We've engaged Dell support, and they have done a deep dive into the storage logs and have determined that it's either a 24/25H2 thing, or something in the middle network-wise. Older versions of Windows 11 have great SMB performance.

When transferring files to Windows Servers of any version, performance is great. We've also noticed that newer Server 2025 instances have the same issue when copying files to the Isilon. Seems like that particular code base of Windows is having issues with 3rd party storage. We've even downgraded SMB dialect to 2.1 and made a host of changes client-side to SMB settings... still seeing the same result. 

Anyone else experiencing this???