It's such a frequently asked question over the last few years that we really need a post we can point people to.
So your cable company rolled out 500Mbps or 1Gbps download speeds, or you have 1Gbps symmetric fiber (GPON/EPON) from ATT or Centurylink or Orange or whoever. You realize your old all in one router from 2009 is not up to the task of handling this, but hey by now stuff should be cheap and available that will handle your new fiber connection right? So you want advice about a router for between $50 and $100 that will route your symmetric gigabit connection while maintaining low latency using SQM and also easy to flash, and you're used to all-in-one devices with wifi, so it should do it all... can someone offer you a selection of 4 or 5 of them to check out for availability in your area?
The answer is NO. Why? Because they don't really exist.
Let's take a look at the math: At 1Gbps using 1500 byte packets, you need to send/receive 83333 packets per second. The packets need to be received by an interrupt, go through the firewall, be inspected, maybe have NAT applied, sent into a queue, the queue calculates rates to avoid over-sending on the link and causing buffers, and then hardware interrupts are serviced to actually send the packet along...
At 1 GHz processing rate, each packet gets 12000 clock cycles of calculation if the CPU is maxed out doing nothing but processing packets.
Evidently in an ideal world, we should have maybe 1.2GHz processors or better, and maybe have two cores at least one can handle interrupts on the receive interface, and one can handle interrupts on the send interface, and they can share the firewall and queueing duties. Let's not forget that there's RAM latency and bandwidth issues if the packets need to go from kernel to userland (like for OpenVPN) and encryption/decryption also for VPNs.
An obvious comparison point is something like the ZBOX Edge CI341 mini PC:
N4100 processor from 1.1 to 2.4GHz with dual LAN ports. It lists on Amazon for $179 without ram, SSD, or Operating system. You can probably turn this into a router for an additional $60 in RAM and SSD and installing OpenWrt, so your final price is $240 for a wired only router that will be quite competent. Now all you need to do is buy $40-120 worth of smart managed switch, and two TP-Link EAP access points, or ubiquiti access points, or maybe some older all-in-one routers running OpenWrt in Dumb AP mode. Let's budget $60 for each access point, and your house needs two of them... so we have:
- x86 Router: $240
- 8 port Smart Switch: $40
- two APs: $120
This is the order of magnitude you should expect to spend to get very good performance on your new Gigabit symmetric line.
Can you do it cheaper? Yes. For example the Raspberry Pi 4 is very popular now. It's more of a development board than an all in one package. The real world performance numbers show that it can route and SQM gigabits of packets using 25% of its CPU capacity or so. If you buy the 2GB version and a case and power supply and the UE 300 USB ethernet dongle, it winds up being closer to $120 than the $240 for the above x86 computer. It's widely available and a good choice, but you're still in the range of $250 after buying your switch and a couple access points. This is more or less the budget version of a good setup. There are also some other good candidate boards which are less widely available but probably very good candidates. the NanoPi R4S or the RockPro64 come to mind.
But at the end of the day, as you move above 500Mbps you should consider the idea that you now have a serious bit of computing to do just to route and firewall and SQM your network, and you'll be better off with a component based network rather than sticking to your all-in-one "wireless router", at least maybe until someone comes out with a good line of multi-gigahertz multi-core multi radio all-in-one devices for 1/4 the cost of a component wise setup. Don't hold your breath over the next 2 years.