@KJK, thanks for the feedback.

Modem is a Technicolor TG789VAC v2

DanFMT wrote

  @KJK, thanks for the feedback.

Modem is a Technicolor TG789VAC v2

  @DanFMT 

OK so DSL, and that one is pretty old and like a lot of ISP CPE that one has pretty customizable firmware letting ISPs remove features, so exact options can vary. If it's not messed with Bridge Mode should be something like Advanced > Local Network > Network Mode > Bridge Mode. Exact place in Web GUI may vary with firmware version but my vague recollection is it was something like that.

If you can't bridge mode because it was disabled then double-NAT with your own router as the designated DMZ isn't the end of the world though not ideal. Another option you could consider would be replacing it entirely with a high quality dedicated modem like a DrayTek Vigor 130 or 160-series (depending on exactly what your DSL is), which I've had good experiences with and also allow significantly more stable connections then the ISP-supplied one. But of course that too depends on whether the ISP allows BYOD there, lots have no problem with it or are even happy to support it, some really want their own stuff for whatever reason.

And I don't want to send you on a wild cost chase beyond your needs, none of this is hundreds or thousnads of dollars but it's not free either. I think a really good stable home network is worth some effort and saves cost/headaches long term as well as making it easier to do other things, but keep an eye on your own budget.

  @sonaric, the ISP has information on how I can configure it in bridge mode. The question is whether I need to do it or not :)

DanFMT wrote

  @sonaric, the ISP has information on how I can configure it in bridge mode. The question is whether I need to do it or not :)

  @DanFMT 

Oh, in that case the answer is "yes, absolutely". Do not double NAT/firewall/etc if you don't absolutely have to. Get the basic ER, put the modem into bridge mode, and then go from there and you'll be fine. Trying to mix and match with multiple network service providers is almost never a good idea and will cause a lot of headaches.