I bought this device about six months ago and was running without issue.

I was in the process of upgrading other TP-Link device firmwares so also upgraded my MR6400v2 from stock firmware to current.

Since then I get constant disconnects saying "sim card not found". A power cycle resolves this issue but I wish to revert back to the original firmware.

Please provide link as older firmwares are not available on the TP-Link sites