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andyh747
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SXT LTE6 Website Hanging Issue

Thu Dec 03, 2020 9:35 pm

Hi All,

Could do with some help and advice on a recent install I've done with an SXT LTE6 kit connected to the Three mobile network.

The connection itself is fine with excellent signal strength, no drops and great speeds in excess of 50mbps download.

The problem is on the client devices (iPhones, iPads, iMac, Windows PC, Windows Phone). The customer is reporting intermittent problems loading websites. They say the loading hangs with the website failing to load on numerous occasions. Sometimes using reload helps and the page loads, other times it doesn't. Happening on all devices apparently.

I had already set the DNS servers to googles on 8.8.8.8 and 8.8.4.4 as this seemed to work well on all other installs I've done. I've changed this back to use dynamic dns servers from Three to see if it has any effect.

Does anyone have any suggestions why this is happening? Anyone else experienced this behaviour? I know there have been reports of some websites hanging when using the Three mobile network in the UK but I've been on Three for two years and the problem has largely disappeared. Reloading always worked to solve the problem but not in this case apparently.

Any help really appreciated as I'm stumped at what's causing this.
 
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Larsa
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Re: SXT LTE6 Website Hanging Issue

Thu Dec 03, 2020 10:13 pm

Any errors in the SXT log? Du you use the internal DNS forwarder? Is there another router behind the SXT LTE6? Some more details like a config (export) would help...
 
andyh747
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Re: SXT LTE6 Website Hanging Issue

Thu Dec 03, 2020 10:55 pm

Thanks for reply.

No errors in the log that I can see. No router behind SXT, it's acting as router.

Config below:
# dec/03/2020 20:41:00 by RouterOS 6.47.8
# software id = BQMS-Z1ZQ
#
# model = RBSXTR
# serial number = xxxxx
/interface ethernet
set [ find default-name=ether1 ] mac-address=48:8F:5A:34:AE:B0
/interface list
add comment=defconf name=WAN
add comment=defconf name=LAN
/interface lte apn
set [ find default=yes ] apn=everywhere name=EE
add apn=3internet default-route-distance=1 name=Three
add apn=payandgo.o2.co.uk default-route-distance=1 name=O2
add apn=wap.vodafone.co.uk authentication=pap default-route-distance=1 name=\
    "Vodafone (Pay Monthly)" user=wap
add apn=pp.vodafone.co.uk authentication=pap default-route-distance=1 name=\
    "Vodafone PAYG" user=wap
/interface lte
set [ find ] apn-profiles=Three band=3 mtu=1400 name=lte1 network-mode=lte
/interface wireless security-profiles
set [ find default=yes ] supplicant-identity=MikroTik
/ip hotspot profile
set [ find default=yes ] html-directory=flash/hotspot
/ip pool
add name=dhcp ranges=192.168.88.10-192.168.88.254
/ip dhcp-server
add address-pool=dhcp disabled=no interface=ether1 lease-time=23h name=\
    defconf
/system logging action
set 1 disk-lines-per-file=2000
add email-to=xxxx name=email target=email
/user group
set full policy="local,telnet,ssh,ftp,reboot,read,write,policy,test,winbox,pas\
    sword,web,sniff,sensitive,api,romon,dude,tikapp"
/ip neighbor discovery-settings
set discover-interface-list=LAN
/interface list member
add comment=defconf interface=ether1 list=LAN
add comment=defconf interface=lte1 list=WAN
add list=LAN
/ip address
add address=192.168.88.1/24 comment=defconf interface=ether1 network=\
    192.168.88.0
/ip cloud
set ddns-enabled=yes
/ip dhcp-server network
add address=192.168.88.0/24 comment=defconf gateway=192.168.88.1
/ip dns
set allow-remote-requests=yes
/ip dns static
add address=192.168.88.1 comment=defconf name=router.lan
/ip firewall filter
add action=accept chain=input dst-port=8291 protocol=tcp
add action=accept chain=input comment=\
    "defconf: accept established,related,untracked" connection-state=\
    established,related,untracked
add action=drop chain=input comment="defconf: drop invalid" connection-state=\
    invalid
add action=accept chain=input comment="defconf: accept ICMP" protocol=icmp
add action=accept chain=input comment=\
    "defconf: accept to local loopback (for CAPsMAN)" dst-address=127.0.0.1
add action=drop chain=input comment="defconf: drop all not coming from LAN" \
    in-interface-list=!LAN
add action=accept chain=forward comment="defconf: accept in ipsec policy" \
    ipsec-policy=in,ipsec
add action=accept chain=forward comment="defconf: accept out ipsec policy" \
    ipsec-policy=out,ipsec
add action=fasttrack-connection chain=forward comment="defconf: fasttrack" \
    connection-state=established,related
add action=accept chain=forward comment=\
    "defconf: accept established,related, untracked" connection-state=\
    established,related,untracked
add action=drop chain=forward comment="defconf: drop invalid" \
    connection-state=invalid
add action=drop chain=forward comment=\
    "defconf: drop all from WAN not DSTNATed" connection-nat-state=!dstnat \
    connection-state=new in-interface-list=WAN
/ip firewall nat
add action=masquerade chain=srcnat comment="defconf: masquerade" \
    ipsec-policy=out,none out-interface-list=WAN
/system clock
set time-zone-name=Europe/London
/system leds
set 0 leds="" type=modem-technology
set 1 leds="" type=interface-activity
/system logging
set 0 action=disk
add action=disk topics=lte
add action=disk topics=gsm
/system scheduler
add disabled=yes interval=6h name="Email Logs" on-event="/log print file=logs\
    \ndelay 10\
    \n/tool e-mail send to=\"xxxxx\" subject=\"\$[/system\
    \_identity get name]  logs\" \\\
    \nbody=\"\$[/system clock get date] log file\" file=logs.txt" policy=\
    ftp,reboot,read,write,policy,test,password,sniff,sensitive,romon \
    start-date=oct/10/2020 start-time=08:55:00
add disabled=yes interval=1d name="System Reboot" on-event="system reboot" \
    policy=ftp,reboot,read,write,policy,test,password,sniff,sensitive,romon \
    start-date=oct/10/2020 start-time=12:00:00
add comment="Runs LTE Monitor script on a schedule." disabled=yes interval=2m \
    name="LTE Reboot" on-event="LTE Monitor" policy=\
    ftp,reboot,read,write,policy,test,password,sniff,sensitive,romon \
    start-date=oct/11/2020 start-time=13:58:00
/system script
add dont-require-permissions=no name="LTE Monitor" owner=admin policy=\
    ftp,reboot,read,write,policy,test,password,sniff,sensitive,romon source=":\
    if ([/ping 8.8.8.8 count=5 size=64 interval=2s]=0) do={\
    \n:tool sms send lte1 \"xxxx\" message=\"LTE Connection Down\"\
    \n:delay 10s\
    \n:interface lte set lte1 disabled=yes\
    \n:delay 5s\
    \n:interface lte set lte1 disabled=no\
    \n}"
/tool e-mail
set address=smtp.gmail.com from=xxxxx port=587 start-tls=yes \
    user=xxxxxx
/tool mac-server
set allowed-interface-list=LAN
/tool mac-server mac-winbox
set allowed-interface-list=LAN
/tool netwatch
add disabled=yes host=8.8.8.8 interval=10s timeout=2s up-script=\
    "tool sms send lte1 \"xxxxx\" message=\"LTE Connection Up\""
/tool sms
set allowed-number=,,,,, port=lte1 receive-enabled=yes
 
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SiB
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Re: SXT LTE6 Website Hanging Issue

Fri Dec 04, 2020 2:07 am

/interface list member
add comment=defconf interface=ether1 list=LAN
add comment=defconf interface=lte1 list=WAN
add list=LAN
add list=LAN <- this can be disable or select interface
/ip dns
set allow-remote-requests=yes
at firewall input you not block incomming DNS ... probably you not have Public IP from ISP but remember about that in future.

All other configuration is normal.
Do you upgrade modem firmware to v026 ?
I see lte have mtu=1400, you do that to fix MSS problems ? Better is a own rule in Mangle. My ISP use package at 1360 :) that better is to wait and what package passing lte1:
tool sniffer quick interface=lte1 duration=10s size=1000-1500 direction=tx ; # watch it few times
tool sniffer quick interface=lte1 duration=10s size=1000-1500 direction=rx ; #try ping your Public IP with differ size package
 
andyh747
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Re: SXT LTE6 Website Hanging Issue

Fri Dec 04, 2020 10:28 am

It appears that the MTU setting was the issue. The default is 1500 which was causing the problem. Changing to 1400 seems to have cured the issue - I changed the MTU last night before grabbing the config but only received notification that it seems to have worked.

The question is why does Mikrotik have the MTU set at 1500 if it causes problems for some connections - only had this with Three mobile. The LTE interface states the actual MTU as 1500 but it’s not so why is it stating an incorrect actual MTU?

Modem software on latest version.
 
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Re: SXT LTE6 Website Hanging Issue

Fri Dec 04, 2020 11:10 am

We're running a number of link using Hi3G in another country and all with default MTU of 1500. The BTS model in this particular case is BTS3900A but in your case might be a different manufactur with a different setup regarding MTU, but as far as I know they are almost always running Huawei. I would check with tech support to verify this is actually the case and why the different MTU.
 
andyh747
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Re: SXT LTE6 Website Hanging Issue

Fri Dec 04, 2020 12:09 pm

Thanks for the reply.

I've had this now at two sites and it's only now I'm realising it was the MTU setting causing the problem. It only happens with Three and no other UK network - I've used Vodafone, O2, and EE with no issues on an MTU of 1500.

Tech support from Three in the UK is non existent. You can't ever get speaking to anyone who hasn't a script in front of them just relaying the questions. None of their staff have any technical knowledge at all unless you get to the higher tiers of support which is almost impossible.

Out of interest can anyone explain the reason why an incorrectly set MTU causes this behaviour on websites? It doesn't affect streaming from what I can tell or speed tests but general web browsing is badly affected.
 
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Re: SXT LTE6 Website Hanging Issue

Fri Dec 04, 2020 1:00 pm

bcs that R11e-LTE6 works with 1500MTU.
Your ISP can work with differ MTU, TTL, CGNAT, QoS FUP/FAP, etc. differ policy and you should check and do some fix.
You can send reqest to mikrotik.com/support to create some auto-mtu detection od mss-clamping as one ON/OFF checkbox. Maybe they consider your request.
 
andyh747
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Re: SXT LTE6 Website Hanging Issue

Fri Dec 04, 2020 1:07 pm

Thanks I'll send a support request.

However it hasn't really answered the question. Three mobile causes problems with an MTU of 1500. I've now confirmed this with an SXT LTE6 and an LHG LTE6. I'd like to know why the MTU being set at 1500 on this particular network causes web page loading to hang. Having researched this a bit it seems many Three mobile network users have complained about the same issue. It would be useful to know why the MTU setting would cause this behaviour.
 
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Re: SXT LTE6 Website Hanging Issue

Fri Dec 04, 2020 1:26 pm

However it hasn't really answered the question. Three mobile causes problems with an MTU of 1500. I've now confirmed this with an SXT LTE6 and an LHG LTE6. I'd like to know why the MTU being set at 1500 on this particular network causes web page loading to hang. Having researched this a bit it seems many Three mobile network users have complained about the same issue. It would be useful to know why the MTU setting would cause this behaviour.
In Poland I not have that problems with main ISP, some MVNO (mobile virtual network operator) and CyfrowyPolsat must be corrected by user.
I say, some ISP must have some correction. Think global. USA TMobile must fix TTL and this mean all other country must to that too ?
We are network person bcs MikroTik it's not a regular SoHo device and some stuff we must fix.
 
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Re: SXT LTE6 Website Hanging Issue

Fri Dec 04, 2020 1:47 pm

Tech support from Three in the UK is non existent. You can't ever get speaking to anyone who hasn't a script in front of them just relaying the questions. None of their staff have any technical knowledge at all unless you get to the higher tiers of support which is almost impossible.

Well, that sounds like typical Hi3G! They are probably using underpaid teens at 1st line support who are picking answers from "LTE for dummies" :-) You can urge the support to get in touch with their mobile broadband technical support (or NOC) for which I know for fact exists in the UK.

I know some people at Hi3G tech support working with the core network that might provide some answers. What part of the UK are we talking about, the GB, Mainland, Northern Ireland etc
 
andyh747
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Re: SXT LTE6 Website Hanging Issue

Fri Dec 04, 2020 1:51 pm

Thanks for that information, really helpful.

This is in mainland UK in the Gloucestershire/Herefordshire region.

Any contacts you have would be great as I'd like to ascertain the reasons for this behaviour.
 
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Re: SXT LTE6 Website Hanging Issue

Fri Dec 04, 2020 1:59 pm

I'll see what I can do but thu it probably have to wait until next week since I'm soon on may way to customer installation, probably for the rest of the day.
 
andyh747
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Re: SXT LTE6 Website Hanging Issue

Fri Dec 04, 2020 2:01 pm

No rush at all and thanks for the help. The system is working fine now according to the customer so changing the MTU has definitely solved the issue for now.
 
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Re: SXT LTE6 Website Hanging Issue

Fri Dec 04, 2020 2:11 pm

You can send reqest to mikrotik.com/support to create some auto-mtu detection od mss-clamping as one ON/OFF checkbox. Maybe they consider your request.

This is what for example the Apple folks are doing when they are pushing out different base band configurations for all operators around the world. This is quite an enormous task which I doubt MT ever will consider (sadly). I really wish there was I way one could configure you own base band profile within the LTE driver.