@TwoBats I suggest you have a look at this thread as well

https://community.tp-link.com/en/home/forum/topic/228326

and maybe post your requests there.

KR

@Solla-topee 

This thread (to which you replied) confirms that regardless of the latest answers that were provided the extenders still broadcast in TKIP mode:

https://community.tp-link.com/en/home/forum/topic/192784

An update from your side is needed by yesterday

KR

@hugo11 

ok thank you all for your help!! I got it worked out and re-associated the extender with my main router and I am all set now abs no longer get the "weak security" warning. Appreciate everyone's help and time!! Thank you again!! We can make my post closed if admin is monitoring this site

@hugo11 Agreed. Have tried all the suggested fixes. Needs option to select extender encryption type

Having experienced the "Weak Security" IOS 14 issue and it taking me a painfully long time to figure out it was the RE450 that was the issue, I have now fixed the problem.

Once I realised that the extender was the problem, I set about trying to figure out why - I naively thought the extender just took in the signal, amplified it and then broadcast an identical but stronger signal. Not so, it applied its own security. Up until that point I had only ever used Tether and it didn't give any information. I then went into the extender via the web interface via the extender's IP address, and whilst some settings were accessible, I didn't see anything about encryption.

I then thought about a firmware update, mine is a V2 extender and its firmware was from 2016. I updated the latest version,  Version 1.0.5 Build 20200914, and now more settings, including security were available. The first thing I noticed was that the extended signals were given different names to those used in the router. In the past the two frequencies from extender had the same names as those from the router. The names I see for the extender signals are TP-Link_Extender_5Ghz and TP-Link_Extender_2,4GHz. I set the security to WPA2-PSK and entered passwords for both (I used the same password I use for the router's wifi).

I then went onto my iPhone and looked at the wifi settings. The two new extender signals had been found and so I chose one and connected to it, but - WEAK SECURITY again.

I checked the signal security for the extender's signal via Windows 10, and it showed it was WPA2 AES. So why was it being flagged as weak security?

In desperation I got the extender to re-scan the networks and re-chose the extender signals - you'll know you've done that because you'll need to reset the passwords. I then did an extender reboot from within the web interface - the web interface will drop out when the reboot executes, but you then just enter the extender's IP address again to re-establish it. 

Hey presto! I now have 4 wifi signals, 2.5GHz and 5.0Ghz from both router and extender, and none of them report weak security.

Happy days!

@TwoBats 

@XYZZ123 

I got this problem fixed on the 450 v2. Same iOS weak signal and turned out to be a problem with their Tether app, with needing a firmware update, and also a poor web interface. Phone reported weak connection, other Apple devices refused to connect. PCs had no problems and connected via AES, all Apple devices after using tether app thought both my router and my extender's connections were TKIP (the tether app sets an outdated mixed mode WPA2 AES + TKIP, which is the problem. My Asus router forces AES only for security and refuses TKIP). So, all networks were killed by the sane router for all Apple devices due insecure outdated mode. Got it solved for 450 by doing:

The order in which things are done matters. First thing, delete the tether app and NEVER reinstall it, it is outdated, problematic trash. Apple devices share wifi connection information across devices. So, I had to forget ALL router and extender-related wifi settings whatsoever on ALL Apple devices, then unplug the extender, then reboot all devices. 

I then did a factory reset of the extender, hooked the extender up to my (pc) laptop via an Ethernet cable. I downloaded the RIGHT firmware for my V2 (the version is marked on a sticker on the back), which was the latest V2 firmware, so as not to mess up the extender. I was careful not to power off or disconnect either device during the firmware update so as not to mess up the extender. When it was done I used the WEB interface only! At this point on V2 I still didn’t get any options for AES in the web interface, UNTIL I changed the mode away from being an extender. I then got the AES settings... so I set it up this way via web interface, then switched the mode back to extender mode. Don't bother connecting devices at this point, you'll have the same problem. Instead, though the WEB interface REBOOT the extender and freshly reconnected and re-inputted passwords on Apple devices. It was only AFTER this extender reboot via web interface that connecting with an Apple device no longer reported weak signal and all devices could connect again via AES and play nice. If I use the stupid "Tether" app EVEN ONCE after this to change a setting, it will again break the network and cause weak security warnings on iOS devices or just kill their connectivity due to smart router refusing the poor security outdated TKIP mode the extender tries to use, so don't do that. Leave the app in the bin where it belongs.

I suspect the problem may be similar for other users. I tried absolutely everything posted, it wasn't until I got it in this magical order that everything went back to normal and started working again!  The company needs to fix their app or remove it from the store and fix the firmware to allow disabling of TKIP (frankly it is bad it doesn't allow this), ...plus prod users to forget the network if they have problems and especially to force an extender reboot via web interface after settings change, for cripes sakes! Their own supposed help docs for this skip this vital step and I ended up with the same issue Lol 😂 All works fine for me now, no weak security, no Asus router refusing weak TKIP connections. Good luck!

@ColinGC you're welcome