I have a MBP and an iMac sitting next to each other, and am temporarily trying to use a neighbors wifi. The MBP is connected to channel 1 on 2.4 GHz, an has a great connection. The iMac has decided to connect on channel 40 on 5 GHz and has a crappy connection. How do I change the wifi channel that a Mac is connected on. I do not have control of the router, and the network name shows up as one device.
iMac, OS X 10.11
You can do this if and only if you have control of the Router.
In the Router, you give each band (2.4 GHZ or 5 GHz) a slightly different name, and change settings on your Mac to connect to the one you prefer.
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You are assuming your connection is not good because of the Wi-Fi. That may not be the reason for the slow connection.
What does an Internet speed test say?
Then try this experiment: Hold down Option while you click on the Wi-Fi Icon on the menBar. You get a snapshot like this older one. Transcribe or screenshot the results:
also, how many Networks do you see?
I explained that initially. But unless you control the Router, you do not have access to separating the two bands from each other, and are at the mercy of the Mac choosing one or the other very bad connections.
Can you make an Ethernet connection, or is your router dead-dead?
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You may be running stuff on the iMac in the background that is hogging the very small bandwidth available on the iMac.
If you have installed software that wastes computer resources on a regular basis, such as speeder-uppers, Cleaners, Optimizers, Virus Scanners, third-party file Sync-ers such as DropBox, OneDrive, or GoogleDrive, or a VPN, it will do busywork and waste scare resources at phenomenal speeds.
Sync-ing an iPhoto library is also know to crater a marginal Wi-Fi connection.
The usual "litmus test" is to restart in safe mode, and measure the speed (such as Internet speed test) there, because it does not load any third-party add-ons.
> OK, I go to SysPref->Network and see the pulldown for "Network Name". I pull that down, and that router has precisely one network name. You can't select 2.4 or 5 there.
As has already been stated, that is because the router is configured to use the same name for both the 2.4 and the 5GHz networks.
This is entirely valid and is designed to let devices (i.e. your Macs) determine which network they want to join.
You. have no control over which one they join under this model. Since both bands have weak signals (as attested by your screenshots), it's largely a crapshoot as to which one it'll join. Differences in system placement/orientation may make a difference, as may chassis construction and (internal) antenna placement) may account for the differences you're seeing.
The normal way of addressing this is to assign different names to the 2.4G and the 5G networks. That removes the ambiguity and enables you to choose which network each devices connects to.
The other option is to get a WiFI extender/remote access point to extend your wireless network and provide greater 5GHz coverage.
Both should have differing and identifable names.
Disconnect the iMAC from the 5GHz network in System Preferences/Network and scan for the 2.4Ghz network name and connect to that instead
2.4GHz networks operate over a much greater distance through with slower speeds; while the frequency band can be congested in built up areas.
Oh and do ensure your neighbour know and agrees to what you are doing.
Based on an RSSI of -85 and a noise of -93 the net signal-to-noise is an appalling 8dB, essentially unusable. Your achieved Tx rate of 14Mbps is based on the absolute simplest modulation technique using one antenna. You have essentially NO signal.
What does the other computer's Option-Wi-Fi snapshot look like?
OK, I go to SysPref->Network and see the pulldown for "Network Name". I pull that down, and that router has precisely one network name. You can't select 2.4 or 5 there.
I was asking you to literally transcribe what you saw in the slower computer. There is MUCH more information there than just RSSI. I would be happy to decode it all and provide additional recommendations.
Go into system preferences/ network not the menu bar item
You will see a pull down menu , just toggle it to join the 2.4GHz network.
The pull down menu will display all broadcast names with in range
Thank you. The owners of the router have given it just one name. From my end, there is no distinction between 2.4 and 5 GHz channels. But what I don't understand is why one machine picked a good channel and another machine picked a crappy one. No question that 5 Ghz doesn't have the range as 2.4 GHz, so it's understandable that 2.4 GHz is working better.
Holding down the option key I also just see one network and, for that matter, the RSSI looks similar on both machines connected to different channels. This suggests that the reception on the iMac is just worse than that on the MBP.
Well, unfortunately, they don't have differing and identifiable names. In my router (which is now on the blink) I certainly do that.
Not sure what you mean by "scan for network names". That's not something I command. I just bring up Network->Advanced->WiFi, and it simply displays the names, of which, in the case of this router, there is precisely one.
I don't think the neighbor will care about any of this, since I'm not actually logging into, or changing anything on his router. The issue is what channel I connect to.
OK, see below for the iMac, which is giving a flaky connection. The issue is why
it is so flaky. I suspect it's because it has decided to connect on 5 Ghz, and I can't
figure out how to tell it not to.
Again, this is sitting RIGHT NEXT to a 2011 MBP, that has a full-bar solid connection
to a 2.4 GHz channel on the router.
[Image Edited by Moderator to Remove Personal Information]
Here's what the wifi looks like on the MBP, which gets strong and reliable connection. Not sure why the params are dimmed. This one is El Capitan, and the iMac is Big Sur.
[Image Edited by Moderator to Remove Personal Information]
That is really not much better. -87 noise and -77 signal is 10dB signal-to-noise, also appalling.
Since that is using older 802.11n, it has slightly different lowest speed. that is one tiny step up from the lowest possible speed, still using only one antenna because the signal is so low.
I would not spend any time wishing to connect to that one instead, they are BOTH unusable.
OK, this is not constructive. I am using the MBP right now, and the connection is rock solid. For the iMac, it is unusable. So I don't know any more than I did before. The question is HOW to make the iMac connection more like the MBP connection. I have to assume that if one channel works well - that's the MBP channel, that's the channel I want the iMac to be using. But I have no clue how to tell the iMac (Big Sur) which channel I want it to use, and I have no clue how it managed to decide to use a channel that was bad.
This is not a router issue. The router is providing a range of channels and frequencies. The question is how to tell that Mac which one I want it to use, and which ones I don't want it to use.
OK, that makes a lot of sense, at least in trying to understand what's going on. Does not make a lot of sense with respect to how the system was designed, in that I see no reason why one shouldn't be able to command what channel a Mac wifi latches onto.
This is a really good reason to give separate names for the 2.4 and 5 GHz channels, because, in principle, they can be best used in different ways. I've always done that for my own router, but I guess others are more casual about it.
change wifi channel on Mac
