Maint: OpenVPN option: remove tun-mtu 1500

- Since it defaults to `1500`
- Affects FastestVPN
- Affects NordVPN
- Affects ProtonVPN
- Affects Surfshark
- Affects Torguard

internal/provider/fastestvpn/openvpnconf.go

@@ -34,7 +34,6 @@ func (f *Fastestvpn) BuildConf(connection models.Connection,
 		"tls-client",
 		"tls-cipher  TLS-DHE-RSA-WITH-AES-256-GCM-SHA384:TLS-DHE-RSA-WITH-AES-256-CBC-SHA256:TLS-DHE-RSA-WITH-CAMELLIA-256-CBC-SHA:TLS-DHE-RSA-WITH-AES-256-CBC-SHA:TLS-RSA-WITH-CAMELLIA-256-CBC-SHA:TLS-RSA-WITH-AES-256-CBC-SHA", //nolint:lll
 		"key-direction 1",
-		"tun-mtu 1500",
 		"tun-mtu-extra 32",
 		"mssfix " + strconv.Itoa(int(settings.MSSFix)), // defaults to 1450
 

internal/provider/nordvpn/openvpnconf.go

@@ -31,7 +31,6 @@ func (n *Nordvpn) BuildConf(connection models.Connection,
 		"tls-exit",
 
 		// Nordvpn specific
-		"tun-mtu 1500",
 		"tun-mtu-extra 32",
 		"mssfix " + strconv.Itoa(int(settings.MSSFix)),
 		"reneg-sec 0",

internal/provider/protonvpn/openvpnconf.go

@@ -32,7 +32,6 @@ func (p *Protonvpn) BuildConf(connection models.Connection,
 		"tls-exit",
 
 		// Protonvpn specific
-		"tun-mtu 1500",
 		"tun-mtu-extra 32",
 		"mssfix " + strconv.Itoa(int(settings.MSSFix)),
 		"reneg-sec 0",

internal/provider/surfshark/openvpnconf.go

@@ -33,7 +33,6 @@ func (s *Surfshark) BuildConf(connection models.Connection,
 		"tls-exit",
 
 		// Surfshark specific
-		"tun-mtu 1500",
 		"tun-mtu-extra 32",
 		"mssfix " + strconv.Itoa(int(settings.MSSFix)),
 		"reneg-sec 0",

internal/provider/torguard/openvpnconf.go

@@ -34,7 +34,6 @@ func (t *Torguard) BuildConf(connection models.Connection,
 		"tls-exit",
 
 		// Torguard specific
-		"tun-mtu 1500",
 		"tun-mtu-extra 32",
 		"mssfix " + strconv.Itoa(int(settings.MSSFix)),
 		"reneg-sec 0",