that unfortunately affects a lot of routers. You can only use the „firmware“ partition size, which in your case seems:
1fc0000 – 6c0000
33292288 – 7077888 = 26214400 = roughly 26Megabyte.
according to that wiki link, it is supported. What exactly are your concerns?
When I first got my WNDR4300v1 I briefly tested and openwrt/ddwrt/stock firmware can be installed repeatedly in any order by tftp flashing without any noticeable issue. 90M flash space wasn't filled up to test when it was made available by ddwrt not sure if that made any difference.
If AC1300 is enough wifi for you and you don't need to shape a gigabit, the Linksys ea6350 v3 with @notengobattery's outstanding optimized build is a startlingly good device which can easily be found for <$30 shipped on ebay. Quad-core 718GHz cpu, 256MB ram, 128MB Flash, dual-firmware, and USB3, which I've tested with a dual Realtek ethernet adapter -- it'll handle a gigabit by itself without taxing the CPU. He's fixed the switch oddness so it can be configured properly in luci, and just generally unleashed all its capability with dozens of well-thought-out optimizations. For anything up to a 500 mbit WAN installation I wouldn't hesitate to recommend it. Also pretty awesome as a NAS, just plug a dual-drive USB 3.1 enclosure into it.
Qualcomm almost got it right with the IPQ4018; unfortunately the internal bandwidth between the CPU and switch/phy/usb is a bit too narrow for routing much more than a gigabit aggregate in both edge and LAN. A great pity because those cores are capable of doing a lot more work than those inexcusably narrow back channels will let it do.
I recently purchased the ODYSSEY - X86J4125 SBC from Seeed and it seems to be working very well with OpenWrt. I have tested the network speed on the onboard Dual Gigabit Ethernet ports and they both reach Gigabit speeds as mentioned. I am also running the OpenWrt system offered by Seeed which already contains many packages. I am already running NAS, Plex Media Server, Adguard Home and VPN on it!
I came across another cheaper board which is this CM4 carrier board and maybe will give it a try later.
I also found out that it's pretty easy to setup the board out-of-the-box because the above OpenWrt system by Seeed already had the Ethernet ports configured. (LAN at 192.168.2.1 and WAN as DHCP client). So I only had to connect the Ethernet ports to get a working router.
So far I am happy with replacing my normal router with an OpenWrt router and exploring more possibilities with OpenWrt!
Isn't Archer C7 v2 grand? >0.5Gbit/sec WiFi throughput from 7 year old device. Sure, 2.4GHz is crap and routing performance is somewhat low w/o offloading but as an AP/smart switch, it is cheap and delivers.
I did a lot of searching for a cheap device that was widely available in the UK and settled on the old BT Home Hub 5A - it was standard issue by one of our biggest internet service providers so there are thousands out there. A few sellers on eBay are selling them used and preloaded with openwrt from £17 about 23 USD. It's easily capable of the 100Mbps down that my provider Virgin Media has as their basic package, but I understand the ADSL in there is a bit outdated - not a problem with a VM cable modem set to modem mode (internal router bypass).