Wow. No shortage of hits on Google for "Thinkpad W520 drops wifi" going back to 2011.

I've also used the Android Wifi Analyzer app for many years to find the best channels for my gear within my home and in dealing with neighbors. Sure would be nice if the neighbors understood that 1, 6, and 11 are the only channels that don't overlap on 2.4GHz.

This is Lenovo's troubleshooting guidance: Frequently drop or intermittent wireless connection Window 7, 8 and 10