Really slow download speeds? I'm convinced it's some sort of DNS issue but I'm stuck

[MattJames]

I've got an RT6600ax router for my home network, with a DS720+ NAS connected for file storage. I've got a Windows desktop connected by ethernet, and a phone connected by wifi.

I'll preface this by saying I am in no way a network expert, and even the words "DNS" fill me with dread. That said, I'm not being useless, I just don't know how to troubleshoot this any more.

Basically my internet speeds are fine according to speedtest (200mb/200mb down/up), streaming is no issue, pages loading fast etc.

But when I'm downloading anything, my download speed is tanking at like 50kb/s. This wasn't an issue yesterday.

I tried manually changing my DNS settings through windows to 8 . 8 . 8 . 8 / 8 . 8 . 4 . 4, which helped, but then downloads were only running at full speed for like 5 seconds, then tanking back down to almost nothing again.

I tried to update the SRM, and am now running SRM 1.3.1-9346 Update 3, but it didn't help. In fact, now the download speeds are slow even if I use the above DNS settings or the automatic ones.

I read some stuff about maybe my ISPs DNS isn't compatible properly with the Synology router? Or else that the NAS is trying to provide the DHCP or something? Honestly I feel like I need a bachelors in network engineering to understand this stuff. I've even tried reinstalling Windows (been meaning to do it), but it hasn't helped.

Can anyone throw any advice my way on what's going on?

 

[Rusty]

I have a question. So this is network speed issue on your NAS or on your PC? Not sure I picked up what device is having the issue here. Or are all device experiencing the same problem?

Maybe start with multiple devices targeting same destination and see how it behaves (pc, phone, nas etc).

So current speedtest results are still good, but real life usage is poor on a single or multiple devices?

Give a bit more info on the actual results and what use cases have you tried.