This thread has been locked for further replies. You can start a new thread to share your ideas or ask questions.Deco XE75 serious lag after firmware update to v1.2.6
This thread has been locked for further replies. You can start a new thread to share your ideas or ask questions.
I recently updated the firmware on my Deco XE75 (AXE5400). The package I purchased included three units and I've had no issues up until now. Before the upgrade, the firmware version I was running was v1.1.11 (XE75 1.0 en_1.1.11 Build 20230302 Rel. 51700_US_EU_JP_CA_AU_up.bin).
Ever since then, all my devices across my house experience serious lag, regardless whether they are connected to the main unit or satellite unit. This has been tested via both wired (1GB Ethernet cable) and wirelessly (with both 802.11ac and 802.11ax devices).
Everything was running smoothly before the upgrade and now I find I cannot revert to the previous version because the web interface will only update the firmware to newer versions!
I've considered completely resetting my router but I understand that firmware will not revert to the original factory installed version, but rather maintain my current version (1.2.6).
Anyone else experiencing this? I'd appreciate any support to help me resolve this, even to get back to firmware v1.1.11!! 
Major update - Resolution!
Firstly, I'd like to thank @IntrovertSins for telling me where I could find v1.2.2 as it's not available on the Canadian TP-Link website. I downloaded it from the UK website, updated my router... and voila! The lag is gone! No muss or fuss with IPv6, and the "stutter" is practically non-existent. This is true for all my devices, including my computers, my apps on my phone/tablet, and even the apps on my smart TV (e.g., YouTube, Prime, etc.). I'm indebted to @IntrovertSins because before this solution, the situation had become untenable. So much so, as it started to have a major impact on my ability to work. MS Team meetings would get messed up and disconnect me completely and/or garble my voice to the point that people couldn't understand me (i.e., connection instability causing audio stutter).
I was apprehensive this downgrade would work since the app prevented me from downgrading to v1.1.11. However, that was not the case and now things seem to be quite stable for the past 6+ hours.
Thank you, thank you, thank you!!! 
Update part 2
For clarity sake, I configured my network with wired back haul (1GB Ethernet switch) . When I first set up my Deco units (Feb 2023), I noticed that the wired back haul wouldn't work and found out it was due to an incompatibility issue with D-Link switches. So I upgraded to a TP-Link switch (Mar 2023) and it has worked flawlessly since then... until I upgraded to firmware v1.2.6. I discovered this incompatibility only after doing much research on the net and various forums.
Update part 3
Today, TP-Link responded to my support request and asked me several questions. They wanted to make sure that my Internet service was stable so I sent them my speed test results with firmware v1.2.6. The results were fine but it took a while to establish the connection. After the download portion of the speed test, the "stutter" then reappeared and the upload portion of the test failed (three times in three attempts). Their last request was for me to connect my computer directly to the modem and run speed test again. This time, the test ran without any hiccups (whatsoever i.e., no lag, no stutter). I tried the latter test (direct connection to the modem) on three different computers and they all worked without issue. This results makes me believe that firmware v1.2.6 is truly the root cause of my problem as I'm not experiencing any issues with firmware v1.2.2.
Update: July 18, 2023
Well, it's been 24 hours since the IPv6 toggle test so here is a quick update. The noticeable improvement (i.e., no lag) has not deteriorated but it now appears that the connection is somewhat temperamental. Initial loads are fine, but it the connection seems to drop as if I was completely disconnected from the Internet. In a few seconds, it would then appear to be working again... until another "stutter" occurs. Here is where I've noticed this happening:
- Web pages - browsing seems fine, then a "page not found" error appears. Simple F5 (refresh) instantly reloads the page without a problem.
- VPN client - my client's VPN keeps dropping (i.e., hiccup, stutter?) until I re-authenticate, at which point it appears fine again... until the next stutter.
- Outlook - while syncing my inboxes, it appears to make it through every account... except the last one! Accessing this account via browser is not a problem, so I can only attribute this to sudden drop in the connection.
So far, it's not catastrophic to my workflow (i.e., work) but it is starting to get annoying. I'm keeping my fingers crossed that this instability doesn't get worse...
TP-Link: is there any "simple" way to rollback the firmware?
Thanks for the feedback. However, I cannot downgrade the firmware through the web interface as I get the following error message. Hence, I was hoping there was another way revert to a previous version of the firmware. 
Another quick update. The lag has returned and toggling the IPv6 does not improve it anymore. Maybe I'm getting used to the lag/stutter but this is really getting on my nerve. So much so that I'm considering going back to my old Netgear router.
Just a quick update for those who are following this thread and are experiencing similar issues as me.
Here are all the following things that I've tried so far:
- Toggle IPv6 settings and rebooting after each change - no noticeable benefit
- Rebooted Deco units individually and collectively on a regular basis - no noticeable benefit
- Tried to downgrade firmware to v1.1.11, (which previously very stable for me!) but system won't allow me (see screenshot above)
Another contributor stated that the CPU was running in excess of 90% (via Deco web interface) but my has been consistently fluctuating between 10% to 40%.
The lag is now back in full force and web pages take anywhere between 5-10 seconds to load, if at all. On several occasions, the website doesn't even load as it just seems to "lose the connection." This happens on various websites and even on my Android apps on my phone/tablet, such as SpeedTest.net, YouTube, etc.
I was hoping that this was a "me" problem and that there was an easy fix, but I'm beginning to think that this is a larger issue that some people have managed to tolerate it and/or do not participate in these community forums.
Thanks again for your continued suggestions.
On the TP-Link support site for here in Canada, I only have access to three firmware versions available for Hardware version 1, specifically v1.1.8, v1.1.10, and v1.1.11 (see screenshot below).
I should add that I upgraded the firmware directly via the Deco app, not from the TP-Link website. When I was on v1.1.11, the app stated that there was a newer firmware version available (i.e., v1.2.6) and hence my willingness to upgrade.
If you don't mind me asking, where did you download v1.1.22 from and are you in Canada/US?
Cheers.
