Just upgraded to an Arris S34, but still only getting 40 Mbps upload speed

Hi there, @drakkan! Thanks for reaching out to us here on the Community Forum! Would you be able to try a test directly from the S34 to a desktop/laptop, without the additional networking equipment to see what speeds you get? Reason being, if you're getting the correct download speed then it is likely we are already configured with the correct bootfile. The true test of speed is going to be a direct connect via ethernet to one laptop/desktop. Let us know the result when you get a chance to try that. Thanks! 

Same question.  I just upgraded to the Arris Surfboard S34, based on the recommended list provided on XFINITY's website (https://assets.xfinity.com/assets/dotcom/projects/cix-4997_compatible-devices/2024.09.18%20Full%20List%20of%20Compatible%20Devices.pdf)

I am limited to 40mbps upload speeds.  I am using a CAT 6 cable directly from the S34 to my laptop.  Download speeds as expected for my 2gpbs tier.  But upload speeds are nowhere near where I am paying for.

What do I need to change or do to achieve those upload speeds?

WOW, I WISH I could get those download speeds.

We just "upgraded" from the gig-extra 1200 plan to the gigx2 2000 speed plan. NOTHING but problems since the swap.

I previously was using their XB8 modem/router with very few issues at all and I used to be able to get over 1200 download on the old plan. Then right after the switch we were only getting around 800 right next to the XB8 and the wifi range got cut in about half too even though their app said their XB8 was receiving over 2000.

MULTIPLE trouble shooting efforts, 3 different XB8's, multiple chat and phone techs, and even techs to the house and NOBODY can even figure out what is wrong MUCH LESS fix my internet and wifi issues.

I finally got so sick of dealing with the XB8 that I completely got rid of their dumb XB8 modem/router and got my own ARRIS S34 modem and a Deco BE65 PRO router mesh system.

STILL do not get anywhere near 2000 download speeds. Barely getting over the 1200 I could get on the old plan and that's only if I'm connected to the Deco BE65 directly with my cat8 ethernet cable. EVEN though the Deco app says it is receiving around 1.8-2.1 from the modem depending on when I test it.

What is even more weird is that if I connect to the MAIN Deco(connected directly to the ARRIS S34 with cat8 ethernet) with my laptop via ethernet I can get about 1600-1800(even though the app still says its receiving higher than that), BUT if I skip the router completely and go connect directly to the ARRIS S34 modem with the laptop and the same ethernet cable I am only getting 300ish down! makes no sense at all!

I am actually getting the 300+ upload speeds but download is trash ever since the internet plan switch.

I am now paying xfinity for up to 2100 down and yet still only getting what I was on the 1200 plan.

I thought the ARRIS S34 might solve my problem but it has not, and now it presents an issue of its own with that connection issue being MUCH slower than the one at the router.

I have run out of ideas on how to fix it.

I too have replaced my old modem with an Arris S34.  My internet plan is 1100/300. I do see 1100+ download but only see 70 up. I have conducted speed test in all configurations, and all reflect similar speed results.  

I have done the following to the modem, turned it off and on, reset to factory setting, checked all connections. I am now wondering how the new modem is listed in my plan based on previous comments and solutions. What else could be done to make the modem meet the speeds of the plan? I believe the solution may be the same as "drakkan" above.

I'm having the same problem. Just moved from Motorola MB8611 to the Arris S34 so that I could take advantage of the new NextGen upload speeds. While I'm getting 2.33 GBps download, I'm still only getting 41 mbps upload.