Issues with IOs / Mac connecting to SE server

[Opinador]

Hello! First time here, so bear with me if I fail to provide the essential details to give a solid picture of what's happening.
I've set up a SE server for 8 users on a W2012 R2, so far so good, only enabled L2TP feature and everything works as expected. BUT, there are two users that cannot access to the vpn from their respective devices. Note that isn't an user related issue. I've tested their credentials on other devices and networks and everything goes smooth.
To be more precise, they have an Iphone 13 and Ipad that connects to the vpn by local wifi and celular network. I can ping the DHCP given IP from server and it responds without packet loss. device seems connected to the VPN, but it cann't browse (SMB, RDP, HTTP..)or do anything with any network device.
Now, if I do the very same with my own Iphone, it connects correctly and can browse the network without issues.

So, it can be anything related with server firewall? (a standard windows firewall that I've been reviewing thoroughtly during these days and I've found no issues whatsoever) if every device works but those two? note that I've already tested it disabling the firewall.
It can be related with the ISP, but then, they're experiencing the same on its home wifi and cellular network. Also, I can ping these devices from SE server.

I'm running out of ideas :(

sorry about my english, obviously I'm not a native speaker
Thank you so much for your time!

[shakibamoshiri]

The cause could be the iPhone devices, specially IOS version.
Already some users (on the forum) reported about issue with L2TP
Examples:
- Windows connects but iPhone cannot connect, is it a server or device issue?
- Connecting iphones via L2TP to SE server