Dell XPS l502x wi-fi speed is dead slow

In my XPS L502X I have been facing the similar problem, my WiFi was dead slow. I had to contact the dell support to resolve my issue.

Go to Control Panel

Power Options

Select Power Plan - check DELL

Change Plan Settings

Change Advanced Power Settings

a pop up comes in on the screen

Expand the - Wireless Adapter Settings

Expand the - Power Saving Mode

Change - On Battery To Maximum Performance - Plugged In To Maximum Performance Restart your system and now your WiFi will work perfectly

• via suggested edit

There's a couple of things I've noticed in regards to wi-fi on laptops which may help.

• Running NetStumbler to scan for other wireless networks on the same channel is a good idea. It might be an idea to try other wireless channels.
• It might be just me but I've found a lot of wireless adapters built-in to laptops to be of variable quality - it might be a fault; is the experience consistent with every network you connect to?
• Obviously check your Windows updates are applied and check for any driver updates.
• Sometimes certain brands of router and adapter just don't work together very well.
• DECT cordless phones and video senders are reputed to cause chaos with wireless networks.
• A known issue with the Dell L502x XPS 15 is the factory installation of the wireless antennae - Unscrew the customer access panel and check if the antennae are correctly connected to the wifi module. This can be done without voiding warranty.

If the experience is consistent regardless of which wireless network you connect to, my guess is that the wireless LAN adapter is at fault. Also, internally the antenna is a wire loop that generally goes around the edges of the screen, if there is a break in the wire, it will also affect your connection performance significantly.