Never tried but you should be able to access it via SSH I would assume.
Not sure why that value changed for you and not me. I don't know what uses it. Maybe it turns back to 0 after a reboot. For now I'd ignore it and try changing wl0.1 to 0 and see if you can now ping between devices.
Real quick before I do that, I was able to SSH into the node router (AX58U). This one has different values for nvram isolate. Lol
@RT-AX58U-8670:/tmp/home/root# nvram show | grep -i isolate size: 79304 bytes (51768 left) wl0.1_ap_isolate=0 wl0.2_ap_isolate=1 wl0.3_ap_isolate=0 wl0.4_ap_isolate=0 wl0.5_ap_isolate=0 wl0_ap_isolate=0 wl1.1_ap_isolate=0 wl1.2_ap_isolate=0 wl1.3_ap_isolate=0 wl1_ap_isolate=0 wl_ap_isolate=0 jorg@RT-AX58U-8670:/tmp/home/root#