Old router as extender?
 

I bought a new router ASUS - RT-AX82U AX5400 Dual-Band WiFi 6 and want to used old router RT-AC1750 as an extender.
My issues is when I try to connect to router page the new router page comes up, can't access the RT-AC1750 page to set as extender or AP access point.
Any input will be appreciated.
Thanks.

You need to connect a hardline to the old router and configure it before you introduce it into your current network.

If it's still providing DHCP, you should get an IP even if it's not going out to the internet. Once you know what the default IP is, you can log into the router and change the role.

If you're still having trouble, hard reset it and start from scratch as the wizard will ask you what role it's supposed to have.

I'm pretty sure that older router supports AIMESH or it will with a firmware update so that would be the preferred way to configure it as an extender. This opens a special channel between the two routers which is better than just using it as repeater.

Not sure why you are having coverage problems, but we were able to relocate our router to a central location (3200 sq ft gardenia), and get great coverage in all locations for both 2G and 5G bands, Xfinity modem/router.

Make sure that the 2 routers have different IP addresses.
Make sure that you shut off DHCP on the 2nd router.

And I agree with VillageTinker. One router, even somewhat centrally located in your house, should provide coverage for the entire home.

Wish you much luck with that, as the 1750 only has media bridge (I call it a pain in the ...) and access point. There is no repeater mode in that model. Aside from that both routers have the same default IP so you would have to connect hardwire to the 1750. I'd highly suggest a factory reset prior to setting it up as an access point.

I have the exact same routers as you and also attempted what you are doing.
I abandoned that idea because 1) As I recall the AC 1750 wouldn't act as an extender and 2) Even if I did succeed, the maximum speed out of the extender router would be half of the main router according to what I read in the ASUS help. I think it said because it would no longer act in a duplex mode. One way at a time communication.

The AX82U is a great router. Really fast if you also have a Wifi 6 capable computer or phone. (Along with appropriate high sped internet service)
Our new computer with a Wifi 6 (AX) card consistently downloads at 675 Meg and 24 up. Yes 675 MB and that is over Wifi. Surprisingly, if Cat6 cabled directly to laptop it is slower.

We don't need that kind of speed but Comcast is providing 600 MB service for $50/month. Couldn't say no.

I have sh*t canned the idea, I was just trying to make use of old equipment. Thanks for the replies and information, much appreciated.
Putting the old router in the spare parts bin!! Trying to move the new router to center of house would never get approval from the powers that be, the center of house would be kitchen or dining room.

Try above the kitchen cabinets, out of sight.

Are you using the Asus app on your phone? The app is very helpful with setting up this option.

Just a few feet toward the center of the house makes s big difference, since router signals degrade faster than you would think. Wifi signals also don’t like water or metal - tends to scatter the signals. Good luck!

smallest house I ever lived in and the strongest connection ever! …

next time just get the Orbi and that problem is solved.

Ubiquity Fan
 

For the difficulties mentioned here and the speed limitations, I switched to the Ubiquity System with various access points.
Works well and excellent remote monitoring.

Moved to kitchen
 

I moved mine from the office to the top of the kitchen cabinet. The height & central location made a world of difference in signal accessibility.
I ran the cable between the cabinets and powered it with the plug above the cabinets.

Just my 2cents: I use a Ubiquity product called Amplifi HD with one additional mesh antenna (Amplifi router cat5e cabled to Spectrum router that has wifi function turned off). That's probably overkill for my home, but, for me, it's more of a tech hobby. Remember, 5G wifi is faster, but doesn't cover as much distance as 2.4G. You can also do speed tests from your phone app to monitor performance in different areas of home. I have a sony tv that uses Android as it's OS and can download the speed test app on the tv and check out the streaming speed of the tv. I then move my mesh antenna around to check for best performance. It's easy to see difference in speed. Again, hobby=$$. Speed test = Ookla at Speedtest by Ookla - The Global Broadband Speed Test