I think I have double nat as I have an orbi installed (router mode) behind a comcast gateway that is broadcasting a wifi signal too and is not in bridge mode.
I have different computers on same orbi network with drastically different speed test numbers 20mps on one desktop and 220mbs on another.
Anyway, I want to change my comcast to bridge mode and put my orbi in ap mode so that orbi is the only thiing broadcasting wifi. The problem is that it's already set up as above and I have over 26 devices hooked to the orbi wirelessly (echo dots, nest cams, thermostats, hue bulbs and sonos, etc.) and I'm afraid I'll lose all connections and have to set everything up again.
What steps in order of detail do you think I should do? enable ap mode on orbi and then log into comcast and enable bridge mode? Will everything come back online to the orbi after doing this since they were originally hooked to the orbi in router mode? Or do you think I will have to start from scratch?
If you are switching the Comcast gateway to bridge mode, then you would want to leave the Orbi in router mode. At least one of the devices needs to be a router. Once the Comcast gatway is in bridge mode, it will stop NAT'ing, but you want to ensure that the Orbi still does NAT.
I basically just went thru and completed as of today a similiary exercise. I replaced one router and several access points with the Orbi. I have as of this posting 47 devices connected out of a possible 70.
You have probably completed this effort, but 1). I had exported my config from my previous router to get a copy of reserved IPs and Ports forwarded. 2). Just go for it and be prepared to make a couple round robins on the various devices to reconnect them. 3). I renamed my SSID so that made it a requirement I visit each device, which I wanted to anyway. If you don't changed SSIDs, you might get lucky and everything reconnets.
AP mode is useful becasue the router also performs network address translation (NAT). With NAT, you have 1 single upstream address that gets translated to multiple downstream (client) addresses. If both your Comcast gateway and Orbi are in router mode, then both are doing NAT, and double-NAT can sometimes interfere with some applications.
In AP mode, the upstream gateway handles all NAT (and security), and the Orbi just sort of transparently connects clients to the gateway.
There is no clear cut ideal choice. Only tradeoffs.
Using the Comcast gateway as a router and the Orbi as an AP allows you to use the Comcast's Wi-Fi in addition to the Orbi's. If you have a huge place that even your Orbi can't cover, then this is an upside. Of course, this would only make sense provided that you can put some distance between the Orbi and Comcast gateway. You can also use the extra Ethernet ports on the gateway to connect devices.
If you put the Comcast gateway into bridge mode and use the Orbi as a router, then you lose the Comcast's Wi-Fi. You can only connect the Orbi to the gateway. All other wired devices must be moved to the Orbi. OTOH, you can leverage the router functions on the Orbi, which may be better than the Comcast gateway. You also have the peace of mind that Comcast can't get into your Orbi. You should assume that Comcast can access the gateway.
Note, if you have IPTV or VOIP services, then it may not be possible to put the Comcast gateway into bridge mode without affecting them.
I'm not sure there's a right or wrong answer here - it just depends on which device you want to manage as your router. Keeping the Comcast gateway as a router and putting the Orbi in AP mode is probably the simplest solution, but other way around should also work. Performance-wise, it shouldn't really matter. They give you the flexibility because not all cable modems are the same - many are simply bridge-only, while others (like yours) have router capabilities as well. So the Orbi has modes to work with either type.
