Thinkpad X240, win7-64bit user here. I tried various driver versions, I tried disabling various features (power management, U-APSD, ...), I tried uninstalling Lenovo Access Connections. Found no good solution but can at least recommend the latest lenovo OEM as the lesser evil.
- 16.6.0.8 (what laptop came with)
- ac mode not working, connectivity OK immediately after reboot/reset but degrading fast, no apparent problems when waking up from sleep
- 17.0.6.1 (.zip distribution for IT admins)
- ac working but performance not good, driver doesn't crash when waking up but connectivity after sleep very bad/nonexistent until complete driver reset (Disable/Enable in Device Manager)
- 17.1.0.19
- ac working but performance not good, driver crashes (error 43) when waking up
- 17.12.0.4 (lenovo OEM, available here)
- ac working, performance good, seems stable, driver crashes (error 43) when waking up
When computer wakes up, just go to Device Manager and Disable and then Enable the AC 7260 adapter (right click). This helps with all driver versions so you don't have to reboot.