download and upload speeds have tanked

Hi everyone,

In 2021, I bought the NZXT Starter Plus from NZXT, and it has honestly been an amazing computer up until recently.

Out of nowhere, my upload and download speeds are now stuck around 18–20 Mbps, and I have no idea why.

Here’s the timeline of what changed:

• I switched internet providers from Spectrum to TDS Telecom due to cost.
• After switching to TDS, my speeds were 600+ Mbps upload and download, no issues.
• I have not used an ethernet cable for about 9 months (WiFi only).
• A few months ago, my partner moved in — around that same time, my speeds dropped significantly.
• My partner consistently gets 600+ Mbps up/down on the same network.
• I am stuck at 18–19 Mbps.

Things I’ve tried:

• Restarted router/modem multiple times
• Factory reset my PC
• General WiFi troubleshooting
• Checked speed tests across multiple sites

Factory resetting my PC did not fix the issue.

At this point, I’m wondering:

• Could this be a WiFi adapter issue?
• A driver issue?
• Something limiting bandwidth on my PC specifically?
• Router settings prioritizing devices?
• 2.4GHz vs 5GHz band issue?
• Failing WiFi card?

Here are my PC specs in case it helps:

• Processor: 11th Gen Intel Core i5-11400F
• RAM: 16GB
• Storage: 500GB SSD + 2TB HDD
• GPU: NVIDIA RTX 2060

I’ll probably post this in a WiFi/networking subreddit too, but I wanted to start here.

What should I try next to properly troubleshoot this?