Double-NAT vs. bridge mode - performance?

[Simon W]

TL;DR - any performance impact with a double-NAT setup vs. bridge mode (using latest gen. ISP supplied hub connected to a RT-AX88U)?

Currently going through the process of upgrading my internet connection - going from 60/20 to hopefully around ~250/40 - as I'll be changing technologies (VDSL2 to G.Fast) this means swapping out my modem to the ISP-supplied (G.Fast compatible) all-in-one hub. My plan was to run this in bridge mode meaning a 1:1 swap and with the rest of my config the same.

However as part of my new contract they've included a "4G Assure" service, basically a 4G USB dongle that automatically fails over in the case of line failure (including some additional smarts such as logging the line fault with the ISP and only failing back once the line is back up and stable). Nothing new technology wise, but pretty neat when it's free and especially with no data caps (also it apparently handles mapping across of fixed IP's.. though I'll only believe this once I've fully tested it!).

Only problem is: 1) 4G dongle locked to only work when connected to the ISP's own hub (which I figured would be the case) and 2) is disabled entirely when the hub is running in bridge mode! <-- disappointing!

So my options:

1. Go with bridge mode as originally planned but without the advantage of the automatic 4G backup (obviously if the line went down for a period of time I could quickly reconfigure to use it)
2. Go with a double-NAT config - I'm otherwise fine with the usual double-NAT pitfall (ie. port mappings more of a pain) so long as there's no performance impact.

Comments and experiences welcomed.. thanks.

 

[ColinTaylor]

Double-NAT in itself shouldn't impact performance in terms of speed or latency in any noticeable way.

However... I don't have any experience with G.Fast but if you have to change your router's WAN connection type (i.e. from PPPoE to Automatic IP) that might have an effect on hardware acceleration. Although if anything a bridged connection using PPPoE is likely to be the one that can't exploit hardware acceleration.

 

[Simon W]

Hmm interesting, thanks, hadn't given any thought to h/w acceleration.

 

[New2This]

I have mine setup in bridge mode(Cable ISP modem/wifi) running AX88U also, But Im also running a DSL line, running dual WAN, in fail over mode

Guess I could try it and see if theres any impact ( double NAT)