I set up a pi4 with OpenWRT a couple years ago that had been working well as a router/gateway/AP for my small home network. I went abroad for a few months in 2023 and left the router running at home so I could access my home network via DDNS. Toward the end of my stay abroad the home network went down and could not be brought back up. When I got home I needed a quick drop-in replacement to hold me over while I diagnosed the issue with the rpi4 and about the only thing I had on hand that I thought might work as a drop-in replacement was an old TP-Link TL-WR1043ND v. 2 that I took out of service about 4 years ago.
Though that router had been working pretty well for me prior to that, I took it out of service at that time because I'd understood it would no longer be supported under OpenWRT due to its hardware limitations. So I was surprised to see, when I started looking up information about it around 1 month ago, that there is a current (23.05.0 r23497-6637af95aa) OpenWRT release available for this thing. I went ahead and flashed that and was off to the races with a working home network til I could find time to diagnose what was going on with the rpi4.
The old router has thus far proved pretty serviceable for my fairly small home LAN so I'd like to keep it on hand for a bit longer as a back-up. So I'm just wondering whether there might be any tweaks I could do to help nurse it along. Like, how about adding a USB drive with a swap file (it does have a USB 2.0 port)? About 77% of available memory is currently in use. About 62% of (ca. 2 MB) disk space is also being used. I did a pretty limited install knowing that the device had limitations, but a few smaller packages fit in just fine. Any tips about ways to help the challenged RAM or disk space on this thing will be appreciated.
And I finally got around to diagnosing the rpi4 problem yesterday: my PNY 32 GB micro SD card had gone bad. I've now replaced it and flashed a fresh OpenWRT onto an 8GB Sandisk micro SD I had laying around (the pi folks recommend either Panasonic or Sandisk). Once I get it all set up again I'll turn it back into the main router/gateway/AP and take the TL-WR1043ND out of service and it will become the back-up in case I will have another problem like that when I go abroad again this year.
Unfortunately 23.05 is the end of the road for 1043v2 (and all 8mb flash/64mb ram).
While it could be "artificially be kept" on life support via custom builds I don't think it will worth the time
Swap on USB is a bad idea, if you need it, you've already lost - and even if you don't, the kernel tends to swap out some parts nevertheless, which will take ages to write or load. As maurer already said, as long as your router works as-is (with current -supported- versions of OpenWrt) and meets your performance expectations, this device will be fine (it's showing its age, flash, RAM, CPU performance, wireless speed, …, but other than that…).
Once upon a time, ~15+ years ago, that might have been sensible - today, not really.
Let's keep in mind, we are talking about a QCA9558 (ath79/ mips 74Kc) single-core SOC, running at 720 MHz, 8/64 and 802.11n single-band wifi, devices you can buy on the used markets for around- and under 10 EUR. The sdhc card & sdhc reader you're going to add would cost more than the remaining resale value of the device.
That's not at all disregarding the features and continued usefulness of this device, as long as you can fit modern (customized/ stripped down <-- imagebuilder, drop opkg and mbedtls (WPA3/ https) and you should be good to go for the next time) OpenWrt into it, depending on your expectations you can easily extend its life time by another 2-3 years. But apart from the (small, but significant in relation to that of the device itself) cost, extroot adds quite a bit of complexity to this in regards to sysupgrades, while not helping at all with the -sufficient-but-limited- RAM size - it's possible, but not really sensible.
New mt7621a+mt7915D devices with DBDC 802.11ax and 128/256 start in the ~15-20 EUR range and the used markets open further opportunities, extroot rarely makes sense today (mounting a data partition somewhere would be another option, but extroot really isn't fun).