Issue with first connection to internet:
Unable to get IP from ISP (Charter).
First with 19.07.3-ar71xx-nand-wndr4300-ubi-factory.img and then with openwrt-19.07.4-ar71xx-nand-wndr4300-squashfs-sysupgrade.tar.
Power cycled modem (ISP supplied Cisco DPC3216 DOCSIS 3.0) and router (WNDR4300v1).
Powered down modem and router, powered up modem waited for boot to complete then powered up router just like many times in the past.
Modem port connected to wan port on wndr4300 router with cat5e cable and wired connection from laptop running Xubuntu to router.
After last hard reset (reset button on back of router) with router offline, logged into the web interface and made 8 changes.
-Synced time and date with browser.
-Set SSH Access Interface to lan.
-In DHCP AND DNS> enabled Log queries.
-In Interface>Wan> disabled Use DNS servers advertised by peer.
-Added OpenDNS IPs in Interface>Wan>Use custom DNS servers.
-Changed MAC in Interface>Wan>Advanced Settings.
-Changed Firewall>Traffic Rules>Allow-Ping and Allow-MLD>Action to Drop and then rebooted the router.
Changed to same MAC I used on this router before switching to OpenWRT. It is also the same MAC I'm using on the new Netgear RAX router that I regret getting (the reason for the earlier than planned install of OpenWRT on my old router). But at least it's usable.
Since my ISP is Charter and my modem is a DOCSIS 3.0, I tried with and with out the wan broadcast flag selected.
Prior to the last hard reset, I connected it to my RAX router (wan port to RAX lan port) after reverting the MAC back to default.
It didn't work at first and it was way past bed time. So I started making changes. Going from more logical to less logical, rebooting the router between most changes. Unfortunately I didn't keep notes this time. Didn't expect it to work. Achieved partial success. I was able to connect to some sites but not others. Most likely double NAT at work.
I look froward to any assistance that may be offered and thank you for your time.