I've pushed a HOTFIX (
wg_server script)
	
	
		
			
				
			
			
				
				CHANGE: Allow use of  'MTU ='  in .conf to override 1420 default - SNB Forums member @Bearnet
				
					
						
							
						
					
					github.com
				
 
			 
		 
	 
Can you please test?
Upgrade using
	
	
	
		Code:
	
	
		e  = Exit Script [?]
E:Option ==> uf dev
	 
 then you should specify 
MTU = 1400 in .conf then restart the 'server' Peer
NOTE: I think you could also specify the 
PostUP  = ip link %i set mtu 1400 directive in the .conf as per 
wg-quick
		 
		
	 
Thanks for the extremely quick response and attempt at resolution!
I upgraded the script and edited the wg21.conf file as follows:
# Home - 192.168.1.0/24
[Interface]
PrivateKey = <redacted>
#Address = 10.8.0.1/32
ListenPort = 51516
MTU = 1400
Running "restart servers" now produces the following output and doesn't work:
E:Option ==> restart servers
    Requesting WireGuard VPN Peer restart for Category 'Servers' (wg21)
    Restarting Wireguard 'server' Peer (wg21)
    wireguard-server1: Wireguard VPN 'Server' Peer (wg21) on XXX:51516 (# Home - 192.168.1.0/24) Terminated
    wireguard-server1: Initialising Wireguard VPN 'Server' Peer (wg21) on XXX:51516
(# Home - 192.168.1.0/24)
Line unrecognized: `MTU=1400'
Configuration parsing error
    ***ERROR Initialisation ABORTED - 'wg setconf wg21 /opt/etc/wireguard.d/wg21.conf' FAILED
Also, I think the latter "1420" in the change you made to wg_server should be "$MTU":
[ -z "$MTU" ] && cmd ifconfig $VPN_ID mtu 1420 || cmd ifconfig $VPN_ID mtu 1420                     # v4.15.5 v1.02
Also, your pointer at adding the PostUp directive to wg21.conf doesn't work:
Line unrecognized: `PostUP=iplink%isetmtu1400'
Configuration parsing error