Run a pair of Ubiquiti Litebeam. If a WiFi extender is working then a proper p2p radio would work better.

Ddwrt can do this with switching gateways via a script that pings thru each ISP. I do it this way with the other isp in a house a block away connected via Ubiquiti litebeams.

Replace them with some cheaper AP Like a tplink.

I would recommend a semi-P2P solution.

Buy an older Ubiquiti Litebeam M5 or M2.4. Buy whichever signal you want to from your main router. The M5 would be Great if your laptop/phone has good 5GHz signal. Set up the LBE outside the shed where you plan to mount it. Give it an static IP based on your Network IP outside the DHCP range (e.g. the main router is 192.168.1.1 and dhcp gives 192.168.1.100-199, so give your LBE the IP 192.168.1.11). Access it again using the new IP, go to Wireless settings, disable AirMax, and connect it to your main router’s WiFi. When its connected you are good to connect it to an AP (below).

Buy any router you can use as an Access Point. A cheap TP-link AX10 or any spare router your have. You’ll need to set it to Access Point mode or disable DHCP at least. Then give it a static IP based on your Network IP outside the DHCP range (e.g. the main router is 192.168.1.1 and dhcp gives 192.168.1.100-199, so give your AP the IP 192.168.1.2).

Connect the LBE to the new “router” (now an Access Point) via lan-to-LAN ports. Careful not to use the LBE’s PoE port. Voila!

I also Like DIY but at this time and Age, getting a 30W type C USB-PD charger, 30W Type C USB-PD powerbank, and a type C 12V activator/adapter woukd be My way to do it. Easier to replace by buying an over-the-counter replacement. That way I can also instruct someone else to buy and replace stuff Without me. It gets tiring to fix things yourself because people dont Even recognize basic electronics. And I can use a 15V type c adapter or 5V for other Network equipment Like an Asus router or a low-power tplink switch.

Another way would be a fast enough charger, to a powerbank that can do passthru, and a dual-head 5-to-12V2A adapter.

But still pretty cool. I remember Building a powerbank Full of AAs and a Couple of LM7805 to give 5V2A to My PSP. Good times.

There are purpose-built equipment for this.

1: P2P WISP such as Ubiquity Litebeam. the old Litebeam M5 is even compatible with 802.11 WiFi when airmax is turned off. My weapon of choice for performance.

2: Mesh routers. What seem to be the common man’s choice these days.

3: Routers that can do Repeater Bridge or Client/Station bridge mode. Easily doable with DDWRT firmware. I only.buy routers that can have DDWRT or OpenWRT because of capabilities like this. Super flexible. Netgear nighthawks and older linksys routers usually can run DDWRT.

4: “WiFi Extenders” or Repeaters with a LAN port.