Say rental is $8/month and approved docsis 3.1 modem is $180 to buy outright. Buying doesn't really make sense unless you will be sticking with the same ISP for at least two years. (And in two years, you might take a promo deal and sign up with another ISP; or move to a different apartment building which doesn't allow your current ISP; or your roommate or SO might decide to take care of connectivity; or technology will advance and you would want a different modem anyway.)

If you quit the ISP in under two years, you can still sell your used modem for a decent chunk of change. If you actually own, you can resell it. I've done this both ways, selling one I no longer use but also buying one used from someone else. So, there's no actual reason for most people to ever pay $180.

Unless you're paying for more than 500mbps internet, you can pay $60 for a docsis 3.0 16x4 modem that will pay itself off in 6-10 months (depending on rental fee). And you can sell it if you move.

ISPs in Australia give the router out for free as long as you agree to a 1 year contract.

Is there an option to not get their router and thus waive the 1-year clause?

Otherwise what you mean is "it is mandatory to lease their router even if you have your own, and you are forced to enter a 1-year minimum contract.".

> Is there an option to not get their router and thus waive the 1-year clause?

Yes. you also have the option to just pay for the ISP router outright.

Oh that's nice! I asked because here in Spain they advertise the same, but you cannot opt out of getting the 1-year lock-in in any way.