Is it possible to run Netgear WAX202 or a WAX206 with OpenWrt directly behind a fiber modem? As far as I know the fiber modem does not do dial-up. So I should be able to enter the access data from the provider somewhere in the WAX202 in OpenWrt GUI. Since WAX202 or WAX206 is only an access point, this is not possible, right? Or is there something to install in OpenWrt to do that?
Otherwise I would need a "real" router between modem and WAX or a router with fiber optic modem.
At least the 206 have a router mode even in the Netgear fw.
In openwrt both modes are supported, on (pretty much) all devices, independent of the feature set of stock fw.
As long as a device has at least two ethernet ports, OpenWrt will come up with a default setup of configuring one as WAN and all others as LAN.
If mt7621 would be a good match as a fibre router (>500 MBit/s) would be another question, yes it can do that, if hardware flow-offloading is able to shine, but the SOC itself is a bit on the lower end for that (so anything beyond the offloaded capabilities would be borderline).
Thanks for your answers....
Currently I use wax202 in router mode. This is connected to the provider router via the WAN port. But there should be a place in OpenWrt where you have to enter the access data? I can't find it right now.
What kind of access data ? PPPoE?
Access data of the internet provider. This one where currently stored in the router of the provider.
That doesn't answer the question though.
But which provider and in which country? Otherwise we'll be guessing for a long time what you need and how it can be achieved.
Ok, it's about Germany and german Telekom. I will get a fiberglass connection in the future. Today I have a Telekom router and behind it an OpenWrt AccessPoint. Behind OpenWrt is my LAN. Today the Telekom router does the dial-up to the internet.
I thought if I have then the fiberglass connection, I only have to get a fiber modem and I can do all without the Telekom router. But I am not sure because I think I have to store my Provider access data somewhere.
I don't know if this will be in this modem or if it must be in the OpenWrt then. E.g. you can enter dial-up data in a router, but I have not found this in OpenWrt yet.
I think before I steal your time, I'll ask the provider directly about this modem, what this exactly do......
202 does as well.
Then ask them what the future connection will be.
Most are Ethernet, and no fruther "data" is needed.
Still doesn't say what kind of connection you currently got ...
But the question is, can you put your current modem in bridge mode ?
I am not sure I understand you correct. Today I have a "normal" DSL connection. Is this your question?
My router today is a Speedport Pro Plus and this have no fiberglass modem.....
DTAG uses PPPoE, but by default will accept any password and username, so it should be no problem to replace the Telekom router with your own OpenWrt router. Telekom for all its occasionally problematic behaviour as ex-monopoly incumbent is a realy good exemplar for how to implement "Routerfreiheit". Just connect your own Router to the "Glasfasermodem2's" ethernetport, configure it for PPPoE and VLAN7 (IIRC).
So to address the modem question, yes the GPON ONT (aka glasfasermodem/glasfasermodem2) needs to be provisioned by the GPON-OLT, but Telekom will provision any compatible GPON ONT, you might have to call them; but if you use the telekom GPON-ONT all you need to do is configure VLAN and PPPoE and you are set.
GPON or potentially XGS-PON, as that is all the Telekom has on offer. There is a minuscule chance that the link is in an cooperation area where another ISP actually supplies the hardware and Telekom just offers its service, in such a case theoretically the link might work over ethernet-over-fiber, but I have not heard of such an example actually existing.
The Glasfasermodem2 is essentially a "passive" bridge between GPON and Ethernet, nothing to configure there or to put in bridge mode (also not much diagnostics to glean).
Even on a Telekom DSL link you can use your own router (and own modem), as I said Telekom is implementing the relevant regulations pretty well and customer friendly.
There is no real "dial-up" happening any more, even with DSL after establishing the connection your are essentially always-on (Telekom will force a PPPoE reconnect every 180 days if I recall correctly).
But you will need to use PPPoE to establish a usable connection to reach the internet. This is, IIRC. partially due to regulatory constrains.
Thank you all for your infos especially for your detailed infos @moeller0
I'll try to summarize what I understand 
All right so when the time comes, I could do without the Telekom router and "only" get along with the modem and my OpenWrt.
Do you mean configure in OpenWrt? So there you can configure "PPPoe" and "VLAN7" (IIRC) then? Or is the modem meant here? At least I find a PPPoe package in OpenWrt but nothing with "IIRC"....
What is means GPON-OLT? I understand GPON ONT in my case is the modem but GPON-OLT?
Exciting topic.
Yes, and you can also get your own modem if you absolutely want to. There is athread on this forum about OpenWrt running SFP gpon ONTs that can be plugged into router with sfp cages directly. However as far as I can see the telekom glasfasermodem2 is pretty decent and low hassle since you only need a router with ethernet wan port.
Ther literally is nothing you can or need to configure on/in a glasfasermodem2, all you need to do is make sure it will be provisioned. For a telekom link where you buy the GF2 I would assume that to be either already done or there being a nice instruction how to get online. But I have no fiber link myself so can not speak from first hand experience.
Optical line termination, the device at ypur ISP where a full PON-tree is connected to the ISPs main network, see e,g.:
Thanks a lot, I feel super informed now
One more point has now occurred to me that I think speaks against the exchange of the Telekomrouter or any Router 
What is about "Telefonie". The Telekomrouter also provided the "IP Telefonie"... there is a DECT Station inside I think...... Even though we not often use this type of telephony anymore, it is still there. This is not possible in OpenWrt or?
I got a gigaset dect IP basestation some years ago, when I wanted to become independent of my ISP's telephony solution in the router; that worked well for Telekom and now works well for O2. Alternatively one can use a second-hand FritzBox to act as VoIP/dect basestation behind an OpenWrt router. In my case what I gained from having OpenWrt as router made up for the inconvenience of needing a separate VoIP-basestation (but that is clearly subjective).