Your budget is really near a https://store.ui.com/us/en/collections/unifi-dream-router/products/udr Unifi dream router. Your family is gonna be way happier with you (0 downtime) and it’ll give you extender options if you ever need it. Unifi is good enough and they update regularly, just disable cloud access stuff and you’re good.

Otherwise you want Opnsense instead of Openwrt. The upgrade process for Openwrt is not automatic, while Opnsense is. Worth it not to have to dote on your router.

And you should get an access point (Unifi something or Tplink Omsomething), wifi is problematic with openwrt and I’m not sure if opensense even lets you do it (haven’t tried).

And you’ll need a switch, dumb or managed, up to you if you want VLANs. The Opnsense box will have just one LAN port, so it requires a switch if you want to plug more than one thing into it. A switch with PoE+ can power the access point directly.

Opnsense needs x64 arch (Intel or AMD CPUs), get a small thin client like a Dell Wyse 5070 extended or HP T730 or that mentioned Fujitsu Futro S720 (its CPU is old tho, you can do better). There may be newer thinclients, you just want a mini PCIe slot to install some Intel gigabit card from eBay with 2 ports. Google power efficient gigabit mini PCIe card - there’s an older model that sucks power and a newer one that doesn’t suck; if you go more than gigabit skip 2.5 on Intel unless you google hard and expect extra power draw. Very limited point to 4 port cards, just go higher gigabit speeds don’t think about multiplexing ports or whatever it is called; and switches switch better than the router can and remove CPU overhead for more actual routing work - 2 port card is the way.

Slap Incus (superior but newer, less guides, LXD is previous name if googling stuff) or Proxmox (good enough, more guides for this) on it, make a VM and pass through the 2 ports of the PCIe cards, slap Opnsense in the VM. Make an LXC container and slap Debian on it and spin up the Unifi controller for your AP. Another container for adguard home or pi hole and you’ve got a box that does the basic nets all in one. The built-in port on the thin client is how you will access the underlying OS, it gets plugged into the switch you’ll have to get. If you got something with 2 gigs of RAM and an AMD Geode/GX or aged Intel Atom CPU I’d just only do Opnsense no hypervisor stuff.

Sorry for the info dump but there’s a lot of angles!

But really, the Unifi dream router is much easier and solves it all-in-one. You need 3 pieces (router, wifi access point, Ethernet switch) for a good experience otherwise.

Yes, it’s recommended to replace the SP4 screen with an SP5 screen - so you can rest easy

Glad yours is usable still! Mine went from fine to unusably flickering within the span of a week, so it set in fast. I babybabied it too hoping to avoid the issue - I guess I just prolonged it till it microsoft wouldn’t fix it anymore. rip fuck this corpo created e waste shit (I use it as a comp strapped to my TV now)

Ditch it, the Surface Pro 4’s are cursed via shit manufacturing.

Its screen will fail sooner or later https://flickergate.com/ . I had one, it started flickering after the “extended” warranty. The display is useless now. Nothing fixes it. At first the flicker stopped if something on the screen moved, so I used this https://github.com/Acie1998/Surface-Pro-Screen-Flicker-Solver to mitigate it. But within a day or two it was worse. I tried a reduced refresh rate, but that did not help by then. It quickly got worse when in use, within minutes after a week of the flickering starting. A used one is just pre-accelerated to its demise.

Replacing the screen - even opening the device - is egregiously dangerous because the screen often cracks when taking it apart. Microsoft abs sucks for making a device that can’t last when it clearly should. (Not to say anything about your specific problems! It sounds like the battery needs to be replaced, but it can run without a battery as far as I know so not sure why it can’t power up with it heavily depleted)

Edit: if you’re going to remove the sceeen, replace the battery and replace the screen with a surface pro 5 screen. They sell them. The batteries get fucked quick cause the heat sink cooks them, so it’s prob the battery causing your problems (mine had shit battery life at its end too)

Here is a blurb from Reddit describing what to get (ifixit apparently sells a surface pro 5 screen as well if you want one degree better than direct China): My advice, if you have a Surface Pro 4 with an Samsung Panel is to replace for an LG Screen from Surface Pro 5/6. You need to buy this LCD cable too for that conversion: M1010537-003

You can check in the device manager which LCD panel you have on your Surface