weird wifi issue - slow card payments

[John Kennedy]

PingPlotter has an excellent graph. Use the free version and store as much data as you deem necessary, then export the data or screenshot it. Compare results to the CC server to a ping plot against the router at the head of the network. If you're having problems to the CC server and not to the router, the problem is at or past the router. If you find the problem internally too, then you know you need to do more troubleshooting on the internal network (switches, cabling, loops, etc).

 

[Big Jim]

Been back on site for a short while today
I used a bat file to run the windows command line ping.
only to 8.8.8.8 (how would I find out the card payment IP ??)
I left it running for around an hour whilst i went off and did something else.

1 machine wired and 1 wireless, no issues on either.
when I initially went on site I ran a couple of manual pings, a couple timed out and some were up around 150ms.

In terms of the complaint, customer has clarified that it was never this slow prior to the unifi installation, and they did have a very busy bank holiday weekend without issue.

I have created a seperate SSID just for the card machines, (i didn't used guest settings though), also this network I created as 5ghz only as the machines were defaulting to 2.4Ghz (just to see if this had any effect)
settings in unifi controller, 2.4ghz was already set to 20mhz, I changed 5ghz to 20 as well now.

insights didn't show much.


onto the starlink, noone on site to give me the credentials for their account, however just downloading the starlink app for my phone did give me some access to it without logging in, there is a page that shows you statistics, there are quite a few random dropouts, most less than 0.1s (according to the app)

Had I just walked in to this place I would have been placing the blame here, but the fact they say it was not like this before tells me it cant be down to that.

Regarding MTU, googling suggests starlink default is 1500 (and can't be changed), i am not sure if this can be set per AP or per SSID within the unifi controller without a gateway ?


Lastly, the "CCTV switch" under the bar, I have for the time being disconnected this, simply because the DVR isn't connected to the network so it wouldn't be able to see those cameras anyway, wasn't sure if the cameras would have been creating constant "noise" trying to reach the DVR.


Card machine performance, all seemed ok today, apart from the last payment taken just as I was about to leave went slowly.

 

[timeshifter]

Are you using the Starlink modem's WiFi? If so then you may be double-NAT ing. Maybe put the Starlink modem in bridge mode, which disables the built in WiFi.

 

[YeOldeStonecat]

Are you using the Starlink modem's WiFi? If so then you may be double-NAT ing. Maybe put the Starlink modem in bridge mode, which disables the built in WiFi.

Agree...we always put in our gateway...and bridge the CPE. Allows us to manage things better for the client. Gives us control of your network, which, if the client wants our help, we need to have.
I've seen quite a few discussions re: MTU with starlink, on sites like reddit with some decent techs that ran into quirks and adjusted that.
Typically it's managed at the gateway, where it's done at the edge, I haven't tried stand alone APs but I "think" you can do it on the Unifi APs.

 

[Big Jim]

Are you using the Starlink modem's WiFi? If so then you may be double-NAT ing. Maybe put the Starlink modem in bridge mode, which disables the built in WiFi.

the starlink router is the only router on site, if I put it in bridge mode as @YeOldeStonecat says it will need another router installing.

I assume with the correct login credentials I will be able to login and disable the wifi, but I wouldn't want to put it in bridge mode.

why would anyone be double Nat'ed ?
the starlink router is handling DHCP on the lan, the Unifi APs are just handling wifi access

 

[John Kennedy]

I recommend trying the PingPlotter with pings to 8.8.8.8 if you don't know the IP/hostname of the CC server (would have to either get from the company or by using a packet sniffer like wireshark or built into a firewall) as well as one to the head of the network. You need to see whether there's any difference between them. Do this with a laptop plugged into a jack where you can plug in a CC machine. If there isn't, and you're not dropping to 8.8.8.8, plug the machine into the same jack and test the CC a bunch of times. If the laptop seems great the entire time and the CC machine has random issues, it might be a coincidence that the change happened after you made changes and it's really the CC company's end. You could also try connecting the CC machines to a separate network somewhere else if possible (it sounds like this would be difficult, though).

+1 for bridging the starlink and using your own router/firewall at the head of the network. 1500 MTU is standard for nearly any regular network device so you shouldn't have to worry about MTU issues if starlink is already using standard 1500 MTU.

 

[Big Jim]

So to put this one to bed.

I went back and unplugged everything, moved the starlink router back to where it was originally and put everything back on wifi.
Went back the next day and the customer confirmed that this had no effect.

So now the "unifi network" has been reinstated, assuming that the customer wasn't trying to pull a fast one ( i have no reason to believe that they were) it is very odd how the issue started straight after the unifi APs were made "live"