Extremely slow WIFI speed

[AggressiveFish]

I ran a speed test on my PC using and I'm getting crappy download speeds of < 10 mbps, I use my phone in the same area and I'm getting 134mbps. What can I do to speed it up? Before even suggesting, I'm not near the router / modem to connect directly and frankly Wifi should not suck like this (I have 500 mbps plan). Help would be greatly appreciated, things known and proven to work. 

[CAguy]

I recently had a similar experience with suddenly slow wifi download speeds using my HP EliteBook 850 laptop, purchased in Dec 2019.  Router wifi download speeds were 150 Mb/s using my Android phone. I was getting only about 1 Mb/s wifi download using the laptop, but wifi upload speed was the max at 10 Mb/s, and using an Ethernet cable to the router resulted in 150 Mb/s download speed. This was an indicator that my issue was very specific to wifi download, and was not an issue with the router. 

I followed various HP and Microsoft troubleshooting steps and finally identified some changes that resolved the slow wifi download. 

Here is the best description for the steps required.

https://www.sonicwall.com/support/knowledge-base/gvc-degraded-internet-throughput-from-local-isp-eve...

Although this solution was related to the use of a VPN network, I have found other sources that implemented the same solution that were not VPN related. 

https://docs.microsoft.com/en-us/powershell/module/netadapter/disable-netadapterrsc?view=win10-ps#ex...

I do occasionally use a SonicWall VPN network on my laptop, so in my case the use of VPN may have been the cause of my problem, thought I have been using VPN since the laptop was new.

The common thread for these solutions is the wifi network adapter "Receive segment coalescing" (Rsc) settings. 

Changes are made such that the Rsc is disabled for ipv4 and ipv6 on the network adapter.

Once these changes are implemented, my wifi download speed resumed to expected speeds of greater than 100 Mb/s using a Netgear 5 GHz router.