windows server 2003 r2 falling off domain

I have a windows 2003 server which keeps moving out of domain. I have been digging in an out for a solution and have come up with 3 of them

1. A registry key for irpstacksize

2. A registry key for netbtdatagram

3. Changing or upgrading to latest tcpip.sys file as I have found a memory leak

First two are straight forward for me but wanted help on the third one. Could anyone tell me where to locate the .dll for the latest tcpip.sys file. I know the OS is out of support and hence relying on the community experience on the same.

Also any other suggestions would do.

If you find this helpful, kindly mark as answer. If you have any queries, please post back as a reply. Will look forward to your feedback. Thanking You Soumyajyoti Biswas