A New fast safe secure router, called  Edgerouter x10.

The least steps are here. 
How to make the great Edgerouter 10x (tm) work day one oobe,  I get 820Mb/s speed (fast.com)
ER-X (short named) setup as a gateway not a bridge (mode)
Tools: 1 Ethernet short cable. costs $4.
Working Coax TV type cable modem ! Arris is best. (all 32-channels paid/active)

The least steps:(are)
  1. RTM read the manual for it, sady no PDF's,  they only have a web pages. (the basics page is it)
  2. Connect PC hardwired direct to ETH0, the left most port front. ethernet wired cable. (POE-in)  POE is dangerous and is off by default.
  3. Set and force the PCs network to IP listed above, to URL bar as 192,168.1.1
  4. Click that in your browser and click ignore certificate errors. (exception1.jpg)
  5. Log-in and set ubnt + ubnt  (un + pw)  day1 new or reset router is this. (default)
  6. Bingo for EDGEMAX as photo below shows, the  firmware WEB GUI (jpg) page:
  7. You must run at least 1 wizard first to make this router function at all.  Wizards > Basic Setup
  8. Set DHCP mode (not static)for automatic and not PPPoE  if using a cable modem.  (if not like this only the ISP can help you, for sure running DSL/ADSL)  <called CLASS OF SERVICE WAN
  9. The firewall is setup automatically using Basic WIZ.
  10. Set a new user name and new password, do that for sure, complex PW for sure, 9chars at least.
  11. Apply changes.
  12. Reboot. (or pull power pack on router and put it back.)
  13. Move PC ethernet cable off eth0 to eth1 (undo step 3) Win10 may want to reboot with a new Router, let it.
  14. Plug in your  modem into Eth0 (marked POE-in) My modem is Arris SB6190 fast as greased lightning.  970Mb/s (fast.com){ at 1am in the morning }
  15. Reboot  the modem and 5min later reboot the router and wait 5min, more. (all LED look normal now) (per your RTM manual)
  16. Done.  (or upgrade firmware if brave, I did to v2.08 hotfix no problems at all.)
It is best to boot the Modem so it can issue your new router a fresh new WAN IP from you ISP DHCP. (wan side) see rule of CPE below.

You now have internet to all Lan ports on the switch. (9 LAN  ports now work) Eth1 to 9)
The firewall is safe. (now)
This is a baseline. (to work from)
If fisky do this. (unique SUBNET IP)

YMMV, your modem may vary.  ( ask your ISP what class of service you have (Cable DHCP, DSL, 3/4/5G, Satellite(Hughesnet), FIOS)  My page here covers but one of six, WAN DHCP.
LAN = local sub net (no WiFI in the box, but I do have WIFI AP box on fixed IP x.x.x.200)
WAN= Wide Area network.
Never use MAC clone on any router, today, it is nothing but  trouble for your ISP then you. Do not to that. (forget you never heard if it , is best ,TODAY)
The modem freezes the IP address for the last router, not power reset, due to the rule of CPE {DOCsis}.
modem is configured for only giving 1 public IP address out !  (that means reboot the modem any time you change out any router)
CPE  for business is not same as residential service, you pay for what you want and get. The ISP controls the DOCSYS.config files not you.
I see some folks in Kansas still run DSL. (learn what you have first, before doing any kind of leap ) Look first, then leap.

version 1.  6 -03-2020