Unfortunately, such things happen and you and/or your actions are not necessarily to blame.
There is a considerable amount of misinformation on the internet and in some cases is based on the general and not the specific.
Overall, it can still be sorted out To do that you need an accurate and fuller understanding of your network and the all of the network devices - wired and wireless.
The only way that I know to do that is with some sketch or diagram presenting the devices, their respective IP addresses, and to some extent the device macs. (macs may or may not be critical at first).
My suggestion is to to get all devices turned on, wait awhile so all can get connected (if they do) and then capture the Nighthawk settings as you did in your post #110.
Do not delete/redact the device IP addresses. Those IP addresses are all (or should be) in one of the private IP address ranges used by thousands of small network. Your Nighthawk router uses the commonly used default value of 192.168.1.1 as does my Linksys router. All of my devices are between 192.168.1.1 and 192.168.1.254. I use selected IP addresses for static devices and a limited range for DHCP devices. Be any given device wired or wireless.
All connected devices must be using IP addresses between 192.168.1.2 and 192.168.1.255 (subnet 255.255.255.0) 192.168.1.0 and 192.168.1.255 should not be being used (non-routable).
FYI from Lifewire:
https://www.lifewire.com/what-is-a-public-ip-address-2625974
https://www.lifewire.com/what-is-a-private-ip-address-2625970
Both links are excellent explanations and tutorials with respect to private IP addresses.
You can easily find other similar links.
PRIVACY:
What you do not want to reveal is your public IP address. Nor do you want to show the full name of any device on the network if that name could potentially reveal someone's identify., MACs are a concern for some folks but that can be mitigated by redacting the first three hexidecimal pairs of the mac address.
You can use "What is my IP" to learn your Public IP address. Generally stays the same but can change.
More homework:
https://www.howtogeek.com/764868/what-is-a-mac-address-and-how-does-it-work/
You need to ensure that on your network there are no devices using the same IP address. Most devices wanting to join the network will request a DHCP IP address from the router (and there should only be one router) and be provided a DHCP IP address from the DHCP IP address range allowed to the router.
End users can control that range of addresses plus use other IP addresses outside of that range for devices that need or require a static (does not change) IP address. Printers, NAS, scanners, Access Points, etc..
Without explicitly knowing what was done when you attempted to enable Access mode not much can be said about what happened. However it is very likely that you changed, deleted, or duplicated some IP address and the router/network got confused. When you reset everything all went back to factory defaults and there were, for example, no duplicate IP addresses and/or macs.
Factory resets are a ready way to recover a "confused" network. Trade-off being that unless you specifically went back to the router and changed the admin name and password your network may be wide open to others who know those default values and how to use them to gain network access.
Another thing: Change the DNS Server IP addreses to Google 8.8.8.8 and 8.8.4.4. There are other options but Google is commonly used. Sometimes the DNS is the ISP, sometimes the network router. Varies.
I use Google.
What also can prove helpful is to disable IPv6.
Unless there are specific and known reasons for changing MAC's leave them alone. Duplicate macs on a network cause problems.
Take some time to regroup. Read the links and use the Nighthawk's device list or even your own sketch to show your network.
For each device ensure that you know its's IP address be it a static IP address or a DHCP IP address (which can and will change with each time the device joins the network.