Telus Wi-Fi B20T AP/Booster Guest Network

[wireless]

As part of new PureFibre residential service, I was given a Telus Wi-Fi Model B20T access point/"booster". On its System Information page it says it's a "Technicolor EWH1350TLU".
On its Wireless configuration page it shows a "Guest" network, which is disabled by default. I enabled it and Wi-Fi clients can connect as expected.
However, it is not behaving as I expect. As I understand it, a Guest network is supposed to allow traffic only to and from the public internet; clients on the Guest Wi-Fi should not be able to see or access any other hosts on the AP's IPv4 subnet (other than the upstream gateway). I'm finding clients on the Guest Wi-Fi can freely access other hosts on the same subnet. There does not appear to be any functional difference between the Primary/"Home" Wi-Fi and the "Guest" Wi-Fi.
Can anyone shed any light on this:

• If you have the same model AP, can you confirm Guest Wi-Fi behaves the same way?
• I can't see any way to manually update the firmware. My current version is 20.3.0336-4949020-20210614101049.13
• Is there an obscure or hidden configuration setting somewhere which will make the Guest network work as I expect?
• Does Telus offer any other "booster"/AP which provides a true Guest Wi-Fi experience? Note: the Actiontec WEB6000Q does not offer any "guest" mode at all
• Any other suggestions appreciated

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