Internet slow with mesh system, unless over VPN

Hello

I have a peculiar problem with a Tenda MW6 mesh system. Once the mesh got deployed (in bridge mode meaning a router still handles DHCP, firewall, NAT etc) most devices work fine but some have serious issues with download speed (upload is fine though).

I have limited capabilities since I'm not at my place, but here's what I have established so far:

1. Most devices work fine - Android phones, iPad, Samsung smart TV - these devices connect mostly over 5GHz band
2. None of the PCs work fine although it's hard to establish what is the problem since all of those (4 laptops in total) have Windows 10 and Intel Wi-Fi cards so it's impossible to pinpoint if it's incompatibility between Intel and Realtek (Tenda uses RTL8812BRH for 5GHz radio).
3. Laptops do not work well on either band - 2.4Ghz nor 5GHz. While both networks have the same SSID and you can't separate them, you can choose to prefer 2.4 or 5 GHz in Intel advanced driver settings so in essence you can choose the band.
4. All notebooks use Win 10 but different Intel cards (6230, AX201, 9461 and something else that I forgot)
5. Nothing changes if you force the notebook to work in 802.11n rather than ac mode - regardless of the band.
6. There is no interference from neighboring networks (it's a house in the countryside)
7. Routing is handled by a TP-Link MR-6400 v5 LTE router with the latest firmware. Tenda MW6 is also using the latest firmware or at least is claims it to be such (online update only).

Here is the catch:

If I enable VPN on my laptop download speed goes up from some 2mbps to roughly 30mbps which is close to max of what the LTE can achieve in this location - this seems to negate the possibility that we are dealing with incompatibility between Intel and Realtek.

That leaves Windows settings or upstream router issues.

However if I connect the same laptop via Ethernet to one of Tenda mesh cubes - in essence making Tenda a wireless bridge - speed is perfectly fine without VPN.

If I connect directly to TP-Link router's Wi-Fi, the speed is fine as well.

Tracert doesn't do much since it times out on a second hop after local router. The IP it times out on is a private range IP but its structure fits IP structure used by the ISP.
Mind you tracert does time out but if you attempt to load the website it will work albeit slowly.

Any ideas here?

 

Sounds like a mismatch in the configuration on the Tenda devices as an Ethernet connection works fine.

Default the Tenda cubes and connect without configuring much of the settings and see what you get for speeds. Posting a tracert will help see where the issue might be.

Enabling VPN to get better speeds also kind of sounds like an ISP route selection issue. Since the VPN takes a different route.

 

I scrapped the config for both Tenda and TP Link LTE router and set it up once more and I have "achieved" the same effect.

The problem is that different parts of the issue point to different reasons. If it was a mismatch for the wireless configuration or lack of compatibility between Realtek and Intel, than using VPN wouldn't make any difference, yet it does.

Since it does make a difference we might assume that is an ISP config issue or route issue or DNS issue but since connecting to Tenda cube via Ethernet also works great, that sort of rules out all of the above.

So I have successfully proved that the issue cannot exist

I have another working theory and another variable to test.

1. Working theory is that Wi-Fi on Tenda interferes with LTE on TP-Link. I know it's possible because when you try to set Wi-FI channel manually on TP-Link, it warns you that it's best to set it on auto as it can interfere with LTE and router will adjust the channel to avoid it.
The downside of this theory is that using Tenda as a wireless bridge works fine suggesting it's not the interference.

2. ISP uses IPs from private range meaning there is another firewall and NAT somewhere "above" so there is another layer of configuration that I have no access to. I will get hold of a different SIM card from different provider to check it the issue persists on a completely different network.
On the other hand I will borrow one of Tenda cubes, take it home and test how it performs connected to my router as an AP. I will re-test in in a different environment (public IP, no LTE etc) but also with the same laptop I have here.

Last thing would be getting hold of an LTE router different than TP-Link or setting up an LTE router myself from a USB modem and an old router running Gargoyle.

Anyway - still hoping someone will point me somewhere with this before I run out of options or patience.

 

It certainly is a bit odd.

I've dealt with this from both the ISP side and customer side though. Everything from primary LTE through HWIC's on Cisco's to backups with Cradle Point setups.

It's a bit odd the PC's have an issue and other devices don't. Wired works great but, over wifi + VPN it works fine. TPL direct wired/wifi works fine.... Tenda seems to be the focus I would be looking at as more of an issue though it's just bridged WIFI nodes.

Have you tried bridging the TPL and making the Tenda the "router" assuming the DHCP / NAT functions?

Double NAT usually isn't much of an issue until you start mucking around with tunneling. LTE handing a private IP "shouldn't" be an issue since most mobile devices get funneled back through a LB before hitting the open internet.

Which provider are you using for LTE? 30mbps seems a bit sluggish...then again on my phone anything VZW related crawls from 1-2mbps up to ~20mbps while T-Mobile based connections are hitting 700/100 speeds.

Grab a WIFI analyzer app and figure out what your RF looks like for utilization and manually set the channels regardless of what the device recommends. automagically selected channels tend to be less than ideal for speed / performance. For instance on 2.4 I set it on 8 and get 200-300mbps and don't have to contend with all of the auto recalculations from dumb devices nearby. For 5ghz I use 160mhz wide and set it on the low end ch 40 or maybe 44 and avoid the default 36 for the same reason.

In general though this is why I avoid / don't recommend "mesh" setups since you get a more stable setup using actual AP's for about the same price. Downside is you have to hardline each AP whereas the convenience of connecting your backhaul on these pods over WIFI makes it simple.

 

TP-Link can't be bridged to just be a LTE modem. It can either work as an LTE router or a "normal" router with one of the LAN ports working as WAN port, but nothing else so it has to be the router in this setup.

As for wireless channels - you can't change them on Tenda. It uses two radios that are set to channel 6 on 2.4GHz and channel 40 for 5Ghz - none of which is an issue since this is a house in the middle of nowhere. The same applies to 30mbps on LTE - that's a very good speed considering where the house is.

For now I switched it all off and setup an old router as a repeater.

I'm gonna take the main Tenda node with me for testing and I'll see how it works in non-LTE, public IP setting.

 

Hmm... being in the middle of nowhere makes for less RF interference.

Ok.. so the Tend is hardcoded which means if you have the TPL WIFI setup you'll want to switch the channels so they don't conflict but provide decent performance.

30mbps in the middle of nowhere is better than I get in the middle of a city with VZW.

I've thought about doing WWAN w/ a 5G M.2 modem but, they're just as pricy as an actual phone. There's only a handful of options when it comes to this sort of thing. There might be some sort of case to be used in housing the modem and providing wifi vs a "hotspot" type setup. Though a HS would work in this application connecting the nodes to the HS over WIFI. I still would opt for the modularity for bein able to upgrade pieces as tech progresses vs self contained setup a HS offers.

I went down this rabbit hole back when my car disabled 3G access to Google Maps and was considering upgrading the 3G modem board in the MMI to regain access but once pulling everything apart to get eyes on the connection it wasn't going to be an option w/o getting really creative and expensive to convert things.

G CPE or 5G Mobile WiFi Router:
D-Link DWR-2010 5G NR NSA Enhanced Gateway
HTC 5G Hub (mobile hotspot with 5” media display)
Huawei 5G CPE Pro
Huawei 5G CPE Pro mmWave
Huawei 5G CPE Pro sub-6GHz
Huawei 5G Outdoor CPE
Huawei 5G Mobile WiFi (mobile hotspot)
Inseego R1000 5G Home Router
Inseego 5G NR MiFi Hotspot
Netgear Nighthawk M2 5G mobile hotspot
Netgear Nighthawk M5 Fusion MR5000 5G mobile hotspot
Nokia FastMile 5G home gateway
Samsung SFG-D0100 5G home gateway
TCL Alcatel 5G mobile hotspot
Gemtek WLTFDQ-154AX Gigabit LTE & 5G CPE
ZTE MC801 5G Indoor WiFi Router
FRITZ!Box 6850
Vodafone GigaCube 5G Router

5G Modules/Data Cards:
Quectel RG510Q 5G NR sub-6GHz and mmWave module
Quectel RM510Q 5G NR sub-6GHz and mmWave module
Quectel AG550Q 5G C-V2X Automotive Grade Module
Sierra Wireless AirPrime 5G module (M.2 form factor)
Telit FM980 5G Module
Telit FM980m 5G Module
Fibocom FB101 5G Module
Fibocom FB150 5G Module
ZTE 5G RF module (series)
SIMCOM SIM8300-M2 5G Sub-6Ghz and mmWave Module
SIMCOM SIM8300 5G NR Sub-6GHz & mmWave Module
SIMCOM SIM8200G-M2 5G NR Module
SIMCOM SIM8200EA-M2 5G NR Sub-6GHz Module
SIMCOM SIM8200G 5G NR Sub-6G Module
LongSung EX510 5G/LTE-FDD/LTE-TDD/HSPA+ Module
LongSung EX520 5G NR M.2 Module
LongSung EX610 5G NR Module

 

The plot thickens.
I tested Tenda MW6 (a single cube) as an AP connected to my router in bridge mode in my location (cable connection, public IP, VPN temporarily disabled on the upstream router for testing) and not only did it work fine without any need to reconfigure (so the same setup that did not work offsite had been simply plugged into a new router in a new location without a single change in config) but it also yielded nice results.

A notebook with Intel 9260 (previously not tested) almost maxed out a 300/50 Internet connection at 287/50 and while testing on LAN it provided a stable 550mbps from local server while connected at 866Mbps (80MHz)

The notebook with Intel 9461 that previously worked at 2mbps unless over VPN, now clocked over 300mbps (LAN test over https) while connected at 433mbps (80MHz). It also did great on external speedtest.

So Tenda is off the hook it seems.

Now onto testing interference with LTE and a different ISP (new SIM card) when I get back on location.

So far I have eliminated almost every variable thus proving the problem cannot exist
I somehow doubt that this will be accepted as a solution to the problem though.

 

Well, that does indeed rule out the Tenda pods.

Make sure you take that testing Ethernet cable back with you as to rule out Layer 1 in the process. Not likely the culprit but, could be the issue.

Could come down to the TPL being the issue and not the SIM / service as well. Another option would be using your phone as a hot spot and configure the pod to connect to that while on site.

 

I did some additional tests and this issue is no less confusing than it used to be.

1. I tested Tenda on a long Ethernet cable to separate if from the LTE modem to minimize interference if there was any - it didn't help.
2. I replaced SIM card with one from a different provider and suddenly everything started working well.
3. I Jerry-rigged a new LTE router using an old TP-Link 1043ND as a router flashed with Gargoyle and a Huwei E5573s-320 MiFi connected via USB to the router working as a modem - that works fine as far as download speeds are concerned with Tenda MW6 working as an AP.

Here is how it looks now:

1. Can't blame WiFi wireless incompatibility as I have tested Tenda MW6 offsite with the same laptop it lags terribly onsite and it worked fine.
2. Can't blame TP-Link TL-MR6400 LTE router as it works fine by itself with main SIM card and works fine with Tenda MW6 attached with a different SIM card.
3. Can't blame the ISP of main SIM card as TP-Link works fine by itself and any device connected via Ethernet cable to Tenda MW6 works fine and a Jerry-rigged router works fine with Tenda MW6 as an AP with this card.

So no one is to blame.

The problem with using the Jerry-rigged LTE router is that the TP-Link working as a router is not very powerful (single core 400MHz CPU and 32MB RAM) and more importantly the Huawei working as LTE modem disconnects from internet after 120 minutes. While it will automatically reconnect, there is not option for it to never disconnect and it's not really something you want to happen if you work remotely. I can fix the first issue by replacing 1043ND with Archer C7 (720MHz 1 core CPU + 128MB RAM) but not the Huawei one.