I would never ever recommend a DSL model of Asus to anyone.
The only Asus DSL modem with a half decent chipset got about 5 minutes of support from Asus.
The DSL-AC88U hasn't had any firmware updates since 2018 and is now officially discontinued.
I still receive frequent firmware updates on my 8 year old RT-AC68U.
It's completely different teams within Asus who work on the RT models than who work on the DSL models.
The RT (router only) models are excellent.
The DSL (integrated modem) models make great doorstops.
@Alex Atkin I don't think you can rule them all out. Some do have Broadcom modem chipsets and are considered to be good devices.
Find me someone with the DSL-AC88U who doesn't regret purchasing it.
The owners thread on ukteckhub was FILLED with bugs Asus were working on (some present since device launch) when they randomly pulled the plug on support.
It has been left with no working multicast, a horrible 5Ghz bug and intermittent crashes
There's a ridiculous number of memory leaks meaning if you are lucky to get to 2 weeks uptime without utilisation hitting 100% and crippling the device then you're doing well.