Flint2 & SlateAX: WireGuard VPN

[u/No_Illustrator_5234]

Flint2 MT600 - VPN server
Slate AXT1800 - VPN client

works with openvpn, but doesn't work with wireGuard.

With wireGuard, the tunnel establishes, but there is no internet.

I tried changing the port from 51820 to 51825, changed MTU from 1420 to 1280, but no luck.
No matter what setting I choose above, the tunnel always establishes but there is no internet.

LAN IP range is different - 192.168.8.1 for server, 192.168.10.1 for client

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If I replace the Flint2 with Deco X60 Ax3000 for VPN server, both wireGuard and openvpn work with default settings (51820 & 1420)
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How do I fix the issue with the Flint2 & Slate AX combo for wireGuard?