Hello!

is there a mikrotik device that allows me to insert 2 simcards and have a 4g/LTE connection and if so, here's the case:

I'm looking for a way to be able to switch from SIM1 to SIM2 without any downtime. meaning I don't want browser downloads let's say to fail or pause forever and stuff like that.
I read and heard about bonding but does it really allow me not to have any internet downtimes and keep whatever is being downloaded to continue normally when switching between sims?

thanks a lot for the help!

The device has to reboot to change SIMs I think but it only takes a minute.

The key to seamless failover is that the remote server doesn't notice any change when the client connection fails over to the other SIM, which requires a machine somewhere in the internet through which you'd tunnel you client traffic. So even with two mobile modems running in parallel, each of them gets its own IP address, and even if both go to internet via the same NAT device of the mobile operator, the port numbers on this NAT device would still be different for connections established via different modems. So what you need is a device with two independent modems, not just two SIMs, and a dual-tunnel setup towards a machine in the internet with a dynamic routing protocol on top of it, so that the only NAT between the client and the server is on that machine.