PTCL (and most ISPs), assign 1 Public IP address to home users. That IP is visible on the internet, it's what represents you online, for example when you post on PG, your Public IP address is recorded.
A private IP or Local IP address is the one assigned to your particular device by your router in a local network.
For example if your router is 192.168.1.1, and you connect a device to the router, the private IP address would be 192.168.1.x
X being a different number every time.
If you don't configure the modem in bridge mode, the Public IP address remains assigned to the crap modem in this case, and just attaching a router without bridging them will cause the following to happen:
-Defeat the purpose of getting a router in the first place, cause if the modem still freezes or whatever, it'll affect the router as well.
-Creates a double NAT, due to having a new set of Private IP ranges.
For example:
Public IP address assigned to your modem is 39.40.40.40, and the LAN of the VDSL modem is 192.168.1.10, connecting a router without bridging would require you to assign a WAN IP address to the router from the same subnet as the VDSL modem, i.e: 192.168.1.x, so your router would then have 192.168.1.15 as it's WAN IP, but then any device you connect to the router would have another separate IP address range, probably 192.168.0.1, causing 2 different subnets in a home network, which is a pain to deal with in some applications, especially P2P online gaming, uTorrent, etc or any applications that require to 'see' your device on the internet.
Bridging the modem and router would directly have the Public IP address assigned to the router rather than the modem, giving you the benefit of having more features to fiddle with in the router and probably better WiFi coverage and throughput if you have a good router.
Hope I cleared things up.
Sent from my SM-G935F
