MTU/MSS problem with Wireguard router

[MikeSouth]

Hi, I've setup OPNsense 24.7.2 as a router as described here https://docs.opnsense.org/manual/how-tos/wireguard-selective-routing.html.
This works great for my linux machines once I've set the Interface MTU to 1420 on the ISC DHCP server.
My Macbooks are not picking up the change and I can't use the router without setting the MTU manually from 1500 to 1420.

I am sure that I've done something wrong, could someone please point me in a direction.
The wireguard instance and the LAN interface do not have a MTU set. I've tried unsuccessfully.

[joezeppy]

Instead of trying to change the MTU on the interfaces, try changing the MTU in the WireGuard instance configuration.  (toggle 'advanced mode' to see the MTU setting).  I have found that I need to set it to 1360 for my road warrior devices.

[MikeSouth]

I've already tried to do that, I went as low as 1280.
I've started with a fresh install, I've tried normalisation, nothing helped besides setting the MTU on the client.

[Phil]

Hi previously i had 40-50Mb/s in upload with Wireguard with MTU 1372 in WG interface but it seems since update it's max 10Mb/s

What happened? is it the same for you?

Best regards

PS: i tried with MSS in lan but the same result
cf:
https://forum.opnsense.org/index.php?topic=21184.0

[Phil]

?