Need help configuring Netgear WNDR3700v1 into an Access Point

[joefuf]

Hopefully I'm coming to you guys with an easy one. I just can't seem to figure it out on my own...

I found a Netgear WNDR3700v1 a few years ago and flashed OpenWrt to it. It's sat on a shelf in the study until this week when everyone in the house has had waaay too much free time and we've begun some spring cleaning.

My father has been working from home and asked if we could use it to hook up his Cisco phone from work. As the router, a DIR 868L managed by our ISP, Optimum/and the modem are in another room, I thought I could turn the Netgear into an access point and repeat the master router's wifi and hook the phone up via Ethernet.

I've followed these two YouTube videos (one and two), however I can't seem to get the thing to get an internet connection.

I've tried deleting the original SSID and joining the master WiFi network in the house. Then I tried adding a SSID with a mode of Access Point. Here are the settings that I entered. But I still seem to be missing something because I'm not getting any internet on the router after the fact.

I've tried adding our 5G network as a Client so that I can make an access point on that frequency too, but I get an error that reads "Failed to confirm apply within 30s, waiting for rollback" and it doesn't apply.

Is there a better way to go about doing this? Can anyone help point out where I'm going wrong?

[slh]

If your main router would be using vanilla OpenWrt as well, WDS/ 4addr would be the ideal solution, but that's not an option if it's not running OpenWrt (technically, a mainline wireless driver based on the nl80211 wireless stack). This leaves only a routed client as potential, but less convenient alternative; I'd recommend against the remaining possibility, relayd, which is conceptually quite broken (not supporting IPv6).

[joefuf]

I'm actually gonna throw in the towel here. I purchased a wifi extender/bridge for $20 so I can just be done with this.