I recently swapped out the wireless card in my Dell XPS 15 for a shiny new Intel 9260. I'm running Ubuntu 17.10 on the Mainline 4.15.12 kernel, alongside a dual-booted Windows 10. The card works exactly as advertised in Windows 10, and I can usually get a stable 300mbps up, 200mbps down.
I have the latest intel microcode for this chip (34.0) and have confirmed with nmcli that it is being loaded.
I've tried some basic fixes for ubuntu wireless trouble, but the only thing that improves my speeds at all so far is disabling 11n mode entirely via adding "11n_disable=1" in iwlwifi.conf. This also kind of works; it's more stable, but restricts me to significantly slower speeds, so i'd prefer to avoid this solution.
I also ran the Ubuntu Forum's wireless info script, uploaded here if it may help in diagnosing the problem.
Does anyone know what might be going on? How is my upload speed so smooth, when the download moves like grass grows? Should I just wait for 18.04 LTS?