As the title says, my wi-fi network is horrible. Let me just start laying out facts:
 

• It's not the internet, because plugging my machine into the router or our NBN box directly gives me speedtest speeds that are close to what was advertised on my plan
• It's not a case of interference. I can have my phone beside the router and it will still only download at about 5-10 Mbps. My PC sits with 1 wall separating it and the router and I still have problems
• It's not just my machine. Many different devices all over the house encounter the same problem. A desktop PC, tablet, laptop and multiple phones all feel the effects of a network that's barely there.
• I've tried changing the channel. I've tried channels 1, 6 and 11. In the past this produced results but not now. It shouldn't matter anyway as my machine doesn't detect any of our neighbours networks. My phone does but it's still only a handful.
• Pretty sure it's not the antennae. They're not broken or snapped and we've only had the device for about a month. It really shouldn't be doing this brand new.
• Even accessing the router (via 192.168...etc) is abysmally slow.
• I've got it emitting the 2.4 and 5ghz networks but I'm pretty sure the only device of ours that can use the 5ghz network is the laptop which I haven't been able to test yet. Regardless, the 5ghz network running smooth doesn't fix the 2.4ghz

I have no idea what I could change at this stage. I mean there's no more options left under the wireless tab to try out. So please tell me, what could possibly be wrong?