With an SFP module according to init7 specifications, there is hardly any reason why this should not work.

When I asked the Delock Product Manager, I received the following answer:
- The media converter 86439 supports 10 Gbps modules according to the MSA standard.
- Please note that only a connection from 10Gbps SFP+ to 1/2.5/5/10 Gbps RJ45 Ethernet is possible.

Hope it helps.

Thanks Anonymous ^^

Init7 says it should work "theoretically", but they haven't done any real tests yet. It's a shame that they don't offer support for Fiber7-X like they do for Fiber7 and then offer the corresponding hardware as a Fiber7-X bundle like they do for Fiber7. Well, you can order the optics and cables from them for 10Gbit/s but no media converter.

Since I don't want to spend almost 190 CHF for nothing, have problems later or send the thing back (think of the environment). I'll probably stay with the 1Gbit/s subscription for now and see how it looks in 12 months. At some point, 10Gbit/s hardware has to be more widely available, now that so many offer it, even if "only" as XGS-PON (except Init7).

I would call Init7 directly. They are really, really helpful and can sell you the SFP module and the cable.
It should also work fine with the router, I had a FW on it for a short time that could "only" handle 1GB.