Upgraded WiFi Card, Performance Still Sux

[Carbo]

We have 3 Dell XPS13 laptops. One is model 9350; the other two are the later model 9360. For some reason the 9350 has been having WiFi issues. With all 3 laptops adjacent to each other and next to the router, both 9360 models show speeds of 866.7 Mbps, while the 9350 is at 650 Mbps. All three laptops show full bars in the WiFi icon.
But if I leave the home office where the router is located the difference is noticeable. The two 9360s are unaffected by the move away, but the WiFi on the 9350 slows considerably and the wifi signal fluctuates. At the moment I'm looking at 1 bar and 130 Mbps. Some quick online research and I figured I'd upgrade the WLAN card in the problem laptop, so I switched to an Intel 8265, (from the stock Dell DW 1820A). But it has made no difference at all. What might be the issue? Thank you.

 

[XavierMace]

What's the antenna configuration on them like?

 

[Carbo]

What's the antenna configuration on them like?

Don't know. Where do I look?

 

[XavierMace]

Best bet is to google for the service manual. The antenna's normally run around the screen.

 

[JackMDS]

If you are not using the Wireless far away from a AP get this and disable the Internal Card.

Try this - https://www.amazon.com/OURLINK-600Mbps-Wireless-Network-Computer/dp/B011T5IF06

 

[razel]

Agree above. Chances are the antenna wire might have been compromised. A family member had an Acer laptop with a strong signal and link speed when right next to the router but barely 15 feet away with a line of sight WiFi was becoming hopeless. I tried a new WiFi card, same, new antenna with old card awesome! Too bad the break in the antenna wire was up in the display and required me de-gluing the display.

I ended up buying a near flush USB AC WiFi adapter an Edimax AC for them and they're happy again.