Hi Kevin,
There is indeed a delay as most Cellular networks are a bit higher than your fixed WAN options. However there are 2 ways that you could use both WAN options with Speed Fusion VPN, before we go into how to reduce the difference in latency. Just to make sure you use the correct one for your application.
If you have cellular on standby in Priority 2 on the dashboard it won’t be connected and only will be used when WAN 1 fails.
There is your delay. The sim card needs to connect to the ISP and this will take time and will delay your SF tunnel failover.
If you have both WAN options on prio 1 in your dashboard the both will be active. In the SF profile you can set Cell 1 on a lower priority so there will be no data in the SF tunnel pushed over Cell 1. The SF tunnel only uses Cell 1 for health checks.
So if you want to reduce the packet loss to a minimum we would be looking at WAN smoothing again. If your data consumption is not to worry, you can use WAN Smoothing on Maximum to get full packet duplication on both WAN’s. This will be really heavy on your data consumption as you duplicate every package. This only works on Maximum as the others will use bonding algorithm and that is a different algorithm where you idealy don’t want to use with different latency connections.
WAN Smoothing explained in a bit more details: SpeedFusion "WAN Smoothing" - #8 by TK_Liew
If data consumption is a thing. You will be looking at hotfailover to cover the most data and therefor you might lose some packages as it transition over to another WAN in your case.
Hope this helps. Let me know if there are any questions.
Hope you had some good holidays and all the best for 2025!