You might get the warning “NETWORK NOT RESPONDING” while playing Warframe. This message indicates that the network between your PC/console and Warframe servers is unstable or takes too long to respond. We have some basic troubleshooting tips here to help you narrow down or perhaps eventually resolve this issue.
Disable IPv6
One additional step you can try is a quick test to see if you are using IPv6: http://test-ipv6.com/. If the result is positive as shown below, we would suggest you to temporarily disable IPv6 on your computer.
Contact ISP
Last but not least, you may also want to contact your ISP for help if you are suffering similar issues while playing other online games or watching online streaming videos.
This document will be updated should any new information on this topic arise.