I've attached screenshots below. They are tested simultaneously.

Hi MMG97, Connectivity issues can be tricky. And getting the best connection results takes some time. They also vary from time to time if you are wireless. I'm on ethernet cable. I have a 55 Mbps plan and I consistently download at 82 Mbps.

First of all, check that your proxy settings are the same in both Firefox and the app that you are using.

Second, I noticed that your speed tests were done using different servers. Always use the same server for comparison.

For some real help with internet connection issues and speedtests go to dslreports.com. They have lots of tools, articles, tips & tricks and a forum to ask questions.

Hope this helps.

Thanks for responding. The proxy settings on both the apps are on 'Auto' and as you said, I kept the servers same this time. Still the same result.

Hi again, I get a little better result when Firefox is set to Use System Proxy Settings.

What stands out to me in your screenshot is the unusually long ping. When I do a speed test the ping is normally 7-9 ms. Try different servers which will give you the fastest ping. They are usually the ones which are the closest to you.

Do you have an anti-virus which might be buffering your connection? Try to disable it temporarily and run another test.

Hi MMG97, Another thought. Did you try re-booting your router/dsl?

Nevermind. I'm overthinking..

I appreciate your help but I've tried everything. Not just on Firefox but this issue is consistent with Chrome and Microsoft Edge too. I don't think there's any issue with my wifi or router because the speeds on cellphones is accurate. I'm starting to think it has something to do with windows update I guess. XD Thank you for your help though. :)

I'm sorry to hear that we couldn't get the issue resolved today. Maybe you can get some answers from tenforums.com or microsoft community forum.

Good Luck!

Well god bless windows' 'uninstall updates' feature. I uninstalled the latest update and the speeds are back to normal. Thank you so much for keeping up with me anyways. :p

Great! I'm glad you found the culprit! Can you keep the update from re-installing automatically?

Maybe this would help (temporarily): https://www.tenforums.com/tutorials/8280-hide-show-windows-updates-windows-10-a.html

I disabled the windows updates for now. If any problem arises I'll try that fix.

OK That's a microsoft tool, btw. Save it for a rainy day.

If there isn't anything else, don't forget to mark your post as solved.

Great work!