On RT-AX58U (running Merlin), for 5 GHz, it shows this list of choices/options:
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Can it be set to
AC/AX only?
The description box is outdated anyway and does not correspond to the choices/options in this menu:
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AC/AX only isn’t an option there, so no.
Set it to N/AC/AX only if it makes you feel better. If your devices all support N or AC or AX, they’ll connect that way anyway. Using “Auto” (leaving A/N/AC/AX all active) won’t matter much unless you have devices you need to upgrade / replace anyway.
See, your devices only pause to share time
while both devices try to transmit or receive at the same time. The good news is that even old A-only devices use OFDM, which as earlier posters said, plays nicer with other devices. Think of this as making A more “forward-compatible” than B, which doesn’t speak OFDM at all.
Your A-only device is more like a friend that speaks the same language and just talks slow. If they’re mostly quiet and reserved, they speak ODFM and can jump in for a word or two and then let the conversation continue. If they interrupt and talk a
lot … well, unlike your friends, you can upgrade chatty slower devices with newer ones.
In contrast, a B-only device on 2.4Ghz is like someone suddenly screaming nearby in a different language (DSSS). They don’t even know how to say “is it my turn to speak?” in ODFM. If you disable B on your router, it won’t start up and encourage a whole separate conversation with someone in DSSS. That’s bad because it can only speak one language at a time, and the DSSS speaker can’t even tell when there’s a break long enough in the ODFM conversation to speak. If it wants to talk it yells in DSSS to ask for a turn (request-to-send or RTS) and the router has to interrupt everyone else and yell back an OK (clear-to-send or CTS), which slows
everyone down even more. So disabling B on 2.4GHz, can have more effect than disabling A on 5GHz.
Keep in mind, preventing A devices (or on 2.4GHz, B devices!) from connecting to
your network, doesn’t affect what your neighbors do. Part 15 FCC rules mean your device must play nice with nearby devices. Even if you disable A on
your 5GHz network, your router’s radio will listen and try its best to allow conversations on the same
channel (not just the same network), including conversations between your neighbor’s old A devices. The only way to get rid of
that problem, is to find a 5GHz channel without any chatty A-only devices nearby, or gift your neighbor a new router you’ve secretly set to N/AC/AX only.
If you think “disabling A or N” will make your router yell over and ignore your neighbor’s A or N devices, it won’t. You can’t turn that off.
You control what devices you have and connect to your network, so the best way to not connect A devices to your network anymore, is … upgrade or replace them.
