Macbook air 2019 randomly not working on specific WIFI

[Xeliath]

The title somewhat explains it. My MacBook air 2019 doesn't connect to one of my WIFI routers. And to make things worse, "wifi diagnostics" seem to have been removed from System Preferences. If I switch to my other router, it works, but when I switch back, it starts by saying "no ip." Then when that disappears, sometimes it works, and sometimes it doesn't.
It crashes seemingly randomly, but also crashes multiple times per day.
The other device that sometimes doesn't work is my dad's Mac Pro (cheese-grater, idk the year.)

The weird thing is that my MacBook air 2014 works, my iPhone works, my Samsung J3 V works, and and every other device works.
Could it be a OS problem, or do you think it is a firmware problem? I suspect one of them, because it has been working fine until just a week or two ago.
No new devices have been connected to the internet on this WIFI that I am aware of, so I don't think it is a IP designation issue.

Please let me know your thoughts

Thanks you!

[kpluck]

1 minute ago, Xeliath said:

And to make things worse, "wifi diagnostics" seem to have been removed from System Preferences.

If you hold down the "option" key while clicking the wifi icon in the menu bar (upper right corner of screen) you will see "Create Diagnostic Report…" and "Open Wireless Diagnostics…". Sorry, don't have much for you other than that. Good luck.

 

-kp

[goto10]

do you have access to that router, to see what channel is using to transmit wifi signal?  you could try change the channel on the router, channel 7 or 9 if is 2.4ghz

 

if it is 5ghz put 112

[Xeliath]

16 hours ago, goto10 said:

do you have access to that router, to see what channel is using to transmit wifi signal?  you could try change the channel on the router, channel 7 or 9 if is 2.4ghz

 

if it is 5ghz put 112

Hi, sorry for responding literally 16 hours after I put the post up
I do not have access to the router, as 192.168.1.1 (the router's ip, obviously) keeps going to "page not responding" on all of my devices.
Should I just restart the router?

[goto10]

yes, but if it keeps happening, the router itself has problems, always access the router via ethernet cable to avoid problems with wifi

[Xeliath]

1 minute ago, goto10 said:

yes, but if it keeps happening, the router itself has problems, always access the router via ethernet cable to avoid problems with wifi

Okay, I'll do that when I get home

[Alex Atkin UK]

22 hours ago, goto10 said:

do you have access to that router, to see what channel is using to transmit wifi signal?  you could try change the channel on the router, channel 7 or 9 if is 2.4ghz

 

if it is 5ghz put 112

No no no, don't do that.  You should only ever use 1, 6 or 11 on 2.4Ghz as this the most common configuration due to US limitations (which sadly impacts the whole world as many routers assume the US limitations).

Anything else will just cause more interference as if your WiFi is on an overlapping channel (such as 7 which overlaps with 6) it wont actually see other networks on that overlapping channel so will clash with them, causing packet loss on all overlapping channels.  You basically screw 2/3 of the spectrum.

 

This sadly happens on too many crappy routers, especially older ISP provided ones, as they simply aren't intelligent enough to pick a sensible channel.  Or worse, people giving bad advice like this, misunderstanding how WiFi channels work.