This right here. In the UK we have a little box (ONT) where the fibre comes into the home that essentially acts as a modem and converts the fibre to ethernet and back again and then they provide a separate wireless router that plugs into it. Other than for my current ISP where I had to specifically request that they enable bridge mode (which they did for free), I’ve never had any issues plugging my own router into the ethernet side of this box.

If your ISP’s wireless router plugs directly into the fibre then you should be able to request that it’s set to bridge mode so that it becomes just a dumb ONT box like we have here. Albeit a large and clunky one.

Contacting the registrar is worth a shot and could be your best bet. I recently did a similar thing except the expiring domain was on a pretty obscure country-TLD with only one registrar. They told me how long the grace period was and then I setup a script to check the availability every minute and alert me when it came up.

Probably not feasible with a .com or similar but they might be able to help in some regard. Edit: though having read about drop catching, that’s definitely your best bet if it’s likely to be sniped!