Double NAT

RouterOS Beginner Basics
1

Hi All,
Been using Mikrotik routers for years at work but have always used Draytek modems with PPPOE pass through so the Mikrotik does the ISP authentication…
Now at home I have upgraded to Fibre and have to use the ISP supplied modem, while this modem does support bridge mode, if I set that up I loose my VOIP
from the ISP…
I have set up the modem to DMZ the Mikrotik 962UiGS-5HacT2HnT but how do I set up the firewall and NAT to forward to my NVR and also accept L2TP/IPSEC connections?

Wan IP is like 203.xxx.xxx.xxx
Modem lan is 176.0.0.1
Mikrotik ETH1 is 176.0.0.2
LAN is 192.168.1.0/24

Any Help Appreciated.

Cheers,
Neil.

2

Do it the same way that you would if the WAN interface had a public IP.
There’s no actual difference between public and private IP addresses except that we all agreed that 192.168.x.x, 172.16-31.x.x, and 10.x.x.x are all “fake” IP addresses.

The only exception to what I’ve just said is if you want to do hairpin NAT for the public IP address. You’ll need to add some extra dstnat rules that match the public IP as the dst-address, and an extra src-nat rule on the LAN side if src-address=192.168.x.0/24 and dst-address=192.168.x.0/24 (use your LAN range here) then action=masquerade.