As of late the RUTX50 download speeds were abysmally slow, I’ve tried a few things, nothing seemed to help - download speed hovers at 2 Mbps, while upload is 50+ Mbps. A week before download speed during the day was in excess of 100+ Mbps during the day. As a last resort I have switched to 4G only and lo and behold, the download speed is up to 60 Mbps. Switched back to 5G/4G mixed mode with n73 band active (only one Telenor in Sweden uses, in Stockholm at least) and download speed is down to 1.7 Mbps. Wasn’t 5G supposed be… faster?
And of course the usual: latest firmware, tried re-set etc etc. Used the router for 3 years without many problems (those that were were resolvable). Now this.
Any thoughts? Somethings seems to be “broken” but is it router or the carrier network?
That has nothing to do with the router. Your cell tower is congested. Very easy to test. Put the SIM card from your router in a 5G capable phone and you will get same speeds.
Just because its 5G doesnt mean anything. If you have thousands of users connected to same cell tower, your connection will literally become unusable. I have seen 0.1Mbps speeds on 5G networks and had to switch down to LTE just so i can get above 1Mbps to send email. Also, different countries have different implementations. Some providers love to cheap out on the main link speed that goes to the tower. 5G is great if its implemented properly. However, nothing can save you from congestion.
Well, that’s the problem. It does not produce same results. I have ordered new SIMs for both phone (Pixel 9 with Graphene) and router - same carrier - and have tested them both in phone and router. Results are fundamentally different. Phone connects to the same tower (at least from what I can see on Opensignal) but speeds are in excess of 150 Mbps (down) indoors on the phone. On the router, with 2 Xpol-2 antennas on a mast on the balcony pointing at the cell mast I’m talking to the speeds on both cards are 1-3 Mbps with 5G enabled and 50+ with 5G disabled. It is mystifying. 
I have tested antennas with VNA, nothing seems to be broken or unbalanced, so I do have 4 working antennas connected to the router.
So partly maybe it is congestion, but that is not the whole story. Part of the reason why I don’t rant about the router is that I switch to the phone hotspot when I’m home and it works fine, but it’s just a pain, and I have such a nice MIMO antenna setup I was really proud of! Half a year back at night I was reaching 790 Mbps with 5G enabled. It was faster than fiber in the house!
I’d like to busy myself in this problem, but I have just too much to do at work now and I don’t have the time. Thinking maybe someone has seen something similar and fixed it.
I like Teltonika hardware, even if I had no end of issues with the router years ago when I got it early on. Unlike many manufacturers they really do fix stuff and over the years RutOS really improved.
The speeds also improve at night (with 5G on), sometimes by a factor of 100! - so yeah, congestion is definitely a apart of it, no argument, but there must be something extra to this.
If the speed improves over night, thats a clear indication of cell tower congestion. On top of that, they may be performing speed reduction on devices that are not identified as phones. There are several providers in my country that do this. SIM card in phone gives full speeds. Put it in a router, you get hard limited at exactly 30Mbps. They use IMEI to identify what kind of device it is.
Yeah. See your point with the throttling, but I did ask the bastards if they do that - according to the contract they should not throttle because it is router, I read the fine print. But… Used to work great though - which is what bugs me to no end!
They will never say that in contract directly. My contract, and many others i saw, clearly say that the provider can not guarantee full speed all the time. Speeds that you, as a end user get, is the maximum what the cell tower can deliver at that moment. That leaves a lot of space for provider to basically do whatever they want. Including throttling.
Obviously, but if they have a contract with several SIM cards, one of which is written in being for use in a router, e.g. not a phone, it’s pretty unreasonable for them to throttle it from 160 to 1.6 Mbps! 
If that is indeed so, well, if I was in US I could probably sue them. I ain’t asking for theoretical “5G speeds”, 75 is plenty for me. If it’s above 100, I could not care what the number is. I don’t mind throttling as long as I get a “reasonable” download speed, but 2 Mbps is ain’t reasonable, damn it! 
There is nothing you can do about too many users on one tower.
Can you point your antennas at a different tower?
Greetings,
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Best Regards,
Justinas
Thank you Justinas. Ticket submitted.
Not really, it’s the only tower I have dLOS to, in fact I have tried mis-align antennas just to test things, but I still maintain connection to the tower in question, the speed just drops. Living in a building covered with sheet metal makes turning directional antennas 180 degrees pretty impossible 
After a modem firmware update, the internet connection speed for 5G went back to normal.
Best Regards,
Justinas
Absolutely amazing support from Teltonika. Really stellar, above and beyond what most companies would go to for a single customer stuck with a weird problem. Many thanks to Justinas.