Recently I managed to fix my horribly designed -and implemented- home network such that computers accessing the internet no longer had to double-NAT. It has been glorious and extremely stable: much better than having to restart the ADSL router/gateway every day or two.
Nothing lasts eternally though, so just a few months later my network has been shaken up again. Our telephone company cancelled the telephone line instead of cancelling a telephone number alias we had set up. This caused our internet ISP to (obviously) stop providing us with internet. When we finally got the telephone line reinstated we appeared as new customers to the ISP. I took advantage to go through with the possibly-daunting task of upgrading our connection to 20/1. I had been wanting to make the switch for a few years, but horror stories had stopped me from doing so. These horror stories include people not having telephone or internet for 3+ months (sometimes stretching to 9 months).
We were out of internet for at least a month anyway, so I thought I might as well dance with the devil and I took the plunge. The ISP has either sorted themselves out, or, we were lucky. 3 weeks later the internet worked.
It dawned on me that I would possibly have to replace our current ADSL modem/gateway with the new one, which wasn't a happy thought. Maybe it would be crippled and the bridging wouldn't work. We'd be back to double-NATting.
For the first few days I decided not to rouse the evil networking spirits and just used the old modem/gateway, which worked fine. I then discovered that my ISP offers an Annex M profile. To take advantage of the extra upload bandwidth I needed to use the new router they had given me. Woe is me.
The router they gave me is a Comtrend HG/CT 536+. It is different from other routers I've had in that instead of just having 4 regular ethernet ports on the back it has two marked as ethernet, and the other two are "HG" and "IPTV". I didn't pay much attention to that until later.
After setting up the router as a bridge and assigning it the proper IP, activating Annex M, etc. I replaced it with the old router. And crossed my fingers. On cue and not to disappoint me, it didn't work. I spent about 20 minutes fiddling with different configuration options, like the ATM service classes (I don't even know what they do). After none of that worked I thought maybe this router had the same problem as the other one, maybe I had to set the mode to bridge from the wizard, otherwise it didn't 'stick'. I couldn't find the wizard though, and I despaired.
Finally I remembered the IPTV and HG ethernet ports. I'm not using IPTV, but what was the HG for? Either on the shipping box or in the manual I had seen 'Home Gateway'...HG. Maybe in bridge mode it only forwards the connection through the HG port? Yeah.
End result: my network hasn't been cannibalized and I now have more bandwidth. More is better, right?